This paper examines the effects of board diversity on firm performance and behavior, focusing on the introduction of female director on board in Japanese listed firms from 2006 to 2015. I found out that the number of female directors on board has not changed over the research time span until 2013, year on that the Prime Minister Shinzo Abe’s plan to revive Japan’s fortunes by increasing women’s participation released. Firms having female directors on board are of large size, younger board and high equity ownership.

I examined the introduction of female director on firm performance and documented that ROA of firms after having first female director on board varies with director’s title and company’s industry. I also examined the effect of female directors on the firm’s CSR and found out that firms having introduced first female director improved their CSR ranking, showing that introduction of female director is used by several companies for symbolic reason.