In this study, we created a Japanese version of the State Hope Scale which assesses the level of hope at the current time, and examined its reliability and validity. Confirmatory factor analysis revealed that the Japanese version of the State Hope Scale had a two-factor structure similar to the original version and good internal consistency. State hope was directly associated with trait hope, state self-esteem, and positive affect; it was inversely correlated with negative affect. These findings support the construct validity of the scale. Furthermore, state hope had unique explanatory power in state anxiety beyond the influence of trait hope, indicating the incremental validity of the scale. In addition, construct validity was demonstrated with a 30-day daily report, which was prepared with college students (N = 154), and showed that state hope was associated with everyday events. Cross-delayed effects modeling also showed associations between state hope, trait hope, and mental health. The results of this study indicate that the State Hope Scale has adequate reliability and validity.