We attempted to develop and validate the Japanese 20-item version of the Attitudes Toward Lesbians and Gay Men Scale (ATLG-J20) based on the original scale developed by Herek (1988). The ATLG-J20 consisted of 20 statements, 10 about lesbians (ATL-J Subscale) and 10 about gay men (ATG-J Subscale), and respondents indicated their levels of agreement or disagreement with those statements. The results showed that ATL-J and ATG-J have factorial validity, reliability, and convergent validity. Moreover, the correlations between those subscales and social desirability responses were not significant. Although there was no significant correlation between those subscales and implicit attitudes, it was suggested that ATLG-J20 is a valid scale as an explicit measure.