In Japan, a married couple must use the same surname to comply with the civil code, and the wife takes her husband’s surname in more than 95 % of married couples. We hypothesized that ambivalent sexism, including hostile and benevolent sexism, is related to the preferred surname choice among unmarried men and women. We discovered the following results. First, men showed averseness to changing their surnames, while women showed acceptance. Second, individuals strongly endorsing hostile sexism were more likely to accept changing their surnames than those endorsing it weakly. Third, men strongly supporting benevolent sexism refused to change their surnames. The relationships between ambivalent sexism and surname choice in Japan were discussed.