The purpose of this study was to investigate the validity of the Japanese version (Kanai, 2013) of the Moral Foundation Questionnaire (MFQ; Graham, Nosek, Haidt, Iyer, Koleva, & Ditto, 2011). In Study 1, we tested the internal validity of the MFQ using data collected from 855 participants, following the procedure by Graham et al. (2011). Analyses revealed that the five-factor model showed the best fit among any other model. In addition, a higher score in In-group, Authority, and Purity was related weakly but significantly to conservative political identity. In Study 2, we tested test-retest reliability as well as the relationships between the MFQ and ideologies, using data collected from 470 participants. The test-retest reliability was relatively low, compared to Graham et al. (2011). The relationships between the MFQ and ideologies were consistent overall with the Moral Foundations Theory. However, we also found several inconsistent results such as a higher score in Purity resulting in agreeing more with a liberal opinion. Usage of the Japanese version of the MFQ in empirical studies was discussed.