2005 AIG Japan Open Tennis Championships – Women's singles

Maria Sharapova was the two-time defending champion, but decided not to participate that year.

Second-seeded Nicole Vaidišová was leading 7–6(7–4), 3–2 in the final against third-seeded Tatiana Golovin, when Golovin retired due to an achilles tendon injury, giving Vaidišová the title. This remains one of the youngest finals in WTA history.

Seeds
• # 🇷🇺 Vera Zvonareva (quarterfinals)

• # 🇨🇿 Nicole Vaidišová (champion)

• # 🇫🇷 Tatiana Golovin (final, retired due to an achilles tendon injury)

• # 🇷🇺 Maria Kirilenko (semifinals)

• # 🇯🇵 Ai Sugiyama (quarterfinals)

• # 🇦🇷 Gisela Dulko (second round)

• # 🇯🇵 Shinobu Asagoe (second round)

• # 🇮🇳 Sania Mirza (semifinals)