HOLLYWOOD — "Ingrid Bergman is the realest thing in these diggings," said an ordinarily caustic Hollywood columnist. The first time you see her you understand the reason for his description of her. She has brought into this capital of artificiality the simplicity and charm of her native Sweden. Unpainted fingernails, skin that doesn't look like icing on a cake, a natural manner, unpretentious clothes - these usual things make her unusual among Hollywood stars.

Miss Bergman's career is marked by no publicity escapades. No stories of outbursts of artistic temperament are told about her. She is rarely seen in those select night clubs where other screen celebrities parade like manikins at a fashion show. The young doctor to whom she was married before she came here is still her husband and from time to time she brings her 5-year-old daughter Pia on the lot with her. Despite her success she remains the unassuming, serious-minded young woman she was when, after much hesitation, she made up her mind to come to this country.

Not long after she arrived, the studio wanted to make some stills of her and the photographer suggested that she raise her skirt ''just a trifle.'' She looked at him, smiled, and remarked: ''But I came here to act, not to dance.'' Some months ago Madame Chiang Kai-shek visited the studio where Miss Bergman was working. All the other stars were dolled up in their best to be presented to the first lady of China. Miss Bergman appeared hatless, dressed in a tailored suit and wearing broad, flat-heeled shoes.

She is not beautiful in the Hollywood sense of the word. The glamour which surrounds her is the glamour of youth and health. Her charm is not dependent upon beauticians and her attractive face would serve better as an ad for a tonic than as one for a cosmetic. It has been used for neither, for she does not believe in endorsing any products.

No one would pick her out as a movie queen. She has stood unrecognized for half an hour waiting on line to see one of her own pictures.

Miss Bergman was working on her new film when, between shots, she posed for me. As Paula in a screen version of ''Angel Street,'' called now ''Gaslight,'' she was dressed in a tight-fitting bustled gown of the Seventies. Her long blond hair fell about her shoulders from beneath a tiny sailor hat. It was surprising how little make-up she had on. Her face is round, her cheek bones well-formed. No lipstick altered the natural contour of her mouth and scant mascara reinforced the long lashes which shade her clear blue eyes. There was none of that unreal look about her which so many actresses feel it is necessary to put on before the camera.

Apart from her appearance, what makes her distinctive is her outlook upon life. About her is none of the gaiety ordinarily associated with this place. Although she believes that her private life is no concern of the public, she had not been posing for me long before she told me about her father, who was a photographer and also an artist.

''He always wanted to make a painting of me,'' she said, ''but he never could get me to pose long enough. I was too restless. All I have by him is a sketch he made when I did not know what he was doing. I am sorry now, but I am one of those people who simply can't sit down and do nothing.

''Even now as I am sitting here I am beginning to worry about my next scene and wondering if I shall know my lines. That is the only thing I don't like about acting: the constant dread I have of forgetting my part. I am what you call a quick study and I can learn my lines under the most trying circumstances. I trained myself to do this when I was a child.

''After my father and mother died, they relatives with whom I lived did not want me to become an actress, but I was constantly studying poems and reciting them for myself in my own room. So that they would not know what I was doing, I kept a phonograph going to drown out my voice.

''Would you mind if I just ran over a few pages of my next scene?'' she asked and so saying she began reading them, her full lips moving as she did so.

In a short time she laid the script aside. It was then I asked what kind of parts she liked the best.

''Serious ones,'' she replied, raising her naturally arched eyebrows. She had been posing in profile. Now, she turned her face toward me as she answered my question.

''Although people seemed to like me in 'Casablanca,' I cared for myself less in that part than in the serious roles I have played. It was for this reason that I was so delighted when, after I saw Mr. Hemingway, he wanted me to play Maria in 'For Whom the Bell Tolls.'

''But you must not forget,'' she said, ''that I come from Sweden and we Swedes are very different from Americans. By nature we are a more serious-minded people. Perhaps it is the ruggedness of the country and the rigors of our climate that make us so. We are not frivolous. The lighter side of life is less important. We even take our pleasures gravely.

''This sober approach to life is evident in all our arts. Our paintings have comparatively little light-heartedness in them and the sunlight they depict is a cold sunlight. One of our most popular authors is that tragic playwright Strindberg whose works never caught on here. I you have ever read his 'Fraulein Julie' you will realize that he does not write the kind of plays that Americans would flock to. Yet I would love to play that part.

''Even our humor is different from yours. There is always a note of fantasy about it. Carl Milles expresses it in some of his sculpture. His quaint dolphins and strange mermen and mermaids are typical of the lighter side of our country and even his dancing girls portray a spirit of meditation.

''Now you understand why I like serious parts better and why my favorite American authors are Hemingway and Steinbeck.''

She went on to compare Hollywood with Rasunda where Swedish films are made. She said that when she came here she just stared about like a ''silly goose,'' although she had been acting in Sweden for some time.

Her first screen appearance took place a quarter of a century ago - she was a year old at the time - when her father made a movie of her birthday party. He continued to take pictures of such parties up to the time of his death when she was 13. She is now doing the same thing for her daughter.

''I always wanted to be an actress,'' she said, ''but my father, who sang well himself, wanted me to be a singer. So to please him I studied singing for three years, but got nowhere. All the time, however, I was acting for my own pleasure. I ransacked the attic for old clothes which I put on while I recited.''

At school in Stockholm her dramatic talent was recognized and when she was 17 she won a scholarship in the Royal Dramatic School. At the end of a year she was on the road to fame and one of her pictures, ''A Woman's Face,'' was voted the best film of 1938 at an international exposition.

Even before, her reputation had spread to this country. Hollywood saw another Garbo in her and tried to lure her here. But the tall young blond actress refused to come. She was doing well, she did not need any more money than she was making and besides she was married to Dr. Lindstrom, then a young dentists. To leave Sweden would mean breaking home ties. It was not until four years ago last April that she arrived here with a nice fat contract.

When she reached Hollywood she realized that she did not fit with its goings-on. She slipped away early from a party given in her honor and went to her room a puzzled young woman.

Notwithstanding all she had heard about the place there were surprises when she started in on her first picture. The extravagances of the studio appalled her. She could not understand the reason for the number of retakes. Buying fresh flowers daily for a scene when paper ones, to her mind, would serve, seemed like throwing money away.

She said nothing and kept much to herself - often a method of becoming unpopular. But strangely enough it did not work that way in her case. People realized that she was shy and strange here and they did not mistake her shyness for standoffishness. When an actress goes to a supermarket and wheels a basketful of provisions up to the checking desk, people are not likely to regard her as upstage.

After she had finished her first picture, ''Intermezzo,'' she went back to Sweden. The next year she returned, followed soon by her husband, who had by then decided to give up dentistry for medicine. They took a small house in Rochester, N.Y., where he attended medical school. Whenever she was not working on a picture or appearing on the stage she flew there. There was but on trouble. Her admirers of both sexes ran her and her husband ragged. They could not even go skating without a gallery.

Ever since she appeared in ''Casablanca,'' Miss Bergman has had an apartment in Beverly Hills where she lives with her daughter. Dr. Lindstrom is an intern in a San Francisco hospital. Nevertheless Miss Bergman is still the housewife and her husband the master of the house.

Like the proverbial busman who goes for a ride on his day off, Miss Bergman goes in for making movies as a hobby. She carries a small movie camera about her and has it near her even when she is working. When I had finished my drawing of her she asked me to pose with it so that she might take a picture. There was something almost childlike about her as she did this.

According to those who have worked with her, she never shows any signs of artistic tantrums. Between shots she can often be seen sitting quietly in her dressing room, reading a novel. She is untiring and seems to radiate a cheerfulness which affects not only her director and fellow actors but also the others at work on the set. Most of ''For Whom the Bell Tolls'' was filmed at an elevation of 8,000 feet. She alone seemed to be unaffected by the altitude. When making an OWI picture in Minnesota she skied to location and laughed at the other members of the company who complained of the cold.

Gregory Ratoff, a hard man to work for, laid aside his boisterous manner when he directed her pictures; he also confessed that at the end of the day he was exhausted while she was still as fresh as when she started. Practically every one of her directors says she is one of the best readers of lines working for the screen and that she is more willing to adopt suggestion than any other star.

Although she accepts criticism and apologizes if she slips on a line, she is more or less set in her ideas about costumes. She refuses to adopt Hollywood's ideas of what she should wear in her pictures, and many a startling gown has been discarded for a simple dress of her own choosing. She is just as positive in her notions concerning make-up and she applies it herself.

''Acting,'' she told me, ''is a hard job which I enjoy. After I have studied my part and get the feel of it, I spend a tremendous amount of time in building up the characterization. I study every sentence, because every work and sentence must add something to the development of the character.

''I work so hard before the camera and on the stage that I have neither the desire nor the energy to act in my private life. There I prefer to be myself and forget all about audiences and look after my family.''