No instrument for assessing impulsiveness has been developed in Japan. After translating the Barratt Impulsiveness Scale 11th version (BIS-11) into Japanese, we investigated reliability and validity in student (n = 34) and worker (n = 416) samples. To assess test-retest reliability, the intraclass coefficient between test and retest was calculated in the student sample. Internal consistency was examined by calculating Cronbach's alpha in the worker sample. To see factor validity, we examined by confirmatory factor analysis whether the three-factor model, proposed by a previous report, fit the data. The results showed that the Japanese version of the BIS-11 had excellent test-retest reliability and acceptable internal consistency reliability. In addition, the Japanese version was judged to have similar factor structure to the original one. The Japanese version of the BIS-11 is a reliable and valid measure and has possible utility for assessing impulsiveness.