Kumagai (written: 熊谷 lit. "bear valley"), also transliterated as Kumagae, is a Japanese surname. Notable people with the surname include:
Andrew Kumagai (熊谷 アンドリュー, born 1993), Japanese footballer
Hitori Kumagai (熊谷 独, born 1936), Japanese writer
Ichiya Kumagae (熊谷 一弥, 1890–1968), Japanese tennis player
Koji Kumagai (熊谷 浩二, born 1975), Japanese footballer
Mami Kumagai (熊谷 真実, born 1960), Japanese actress
Masahiko Kumagai (熊谷 雅彦, born 1975), Japanese footballer
Mie Kumagai, Japanese video game producer
Motoichi Kumagai (熊谷 元一, 1909–2010), Japanese photographer
Naoko Kumagai (熊谷 直子, born 1971), Japanese kickboxer
Kumagai Naozane (熊谷 次郎 直実, 1141–1207/1208), Japanese soldier
Noriaki Kumagai (born 1970), Japanese drummer
Saki Kumagai (熊谷 紗希, born 1990), Japanese footballer
Seiji Kumagai (熊谷 誠二, born 1967), Japanese voice actor
Fictional characters:
Kumagai (熊谷), character in the manga series Binbō-gami ga!
