The purposes of the present study were to examine reliability and validity of Japanese version of Rasmussen's Ego Identity Scale (REIS). REIS, Trait-Anxiety Inventory, Identity Diffusion Scale, and Self-Esteem Scale were administered to 245 university students. Reliability of Rasmussen's Scale were assessed by split-half method and Cronbach's alpha coefficient. REIS were also administered a week later in order to analyze test-retest reliability. Correlations were performed between REIS and other three measures to examine concurrent and criterion-related validity. The results showed that REIS was a reliable and valid measure for Japanese university students. The necessity of future studies using this scale was suggested.