Although conservative parties in developed countries are becoming more positive about women’s labor force participation, serious economic gender gaps persist in some conservative welfare regimes. By focusing on Japan as a most-likely case, this article reexamines the view that emphasizes conservative parties’ preference for traditional gender roles as a key factor contributing to policies that negatively affect gender equality. Analyses using text data from parliamentary statements reveal that parties’ preference for class equality, held by both conservative and leftist parties, contributes to a tax policy that suppresses women’s labor force participation. The findings illuminate a tradeoff between class and gender equality and provide implications for how conservative welfare regimes can achieve higher levels of economic gender equality.