Kusaka (written: 日下 or 草鹿) is a Japanese surname. Notable people with the surname include:
Chihiro Kusaka (日下 ちひろ) (born 1978), Japanese voice actress
Hidenori Kusaka (日下 秀憲), Japanese manga artist
Jinichi Kusaka (草鹿 任一) (1888–1972), Imperial Japanese Navy admiral
Maryanne Kusaka, American politician
Ryūnosuke Kusaka (草鹿 龍之介) (1893–1971), Imperial Japanese Navy admiral
Shin Kusaka (日下 慎), Japanese actor
Takeshi Kusaka (日下 武史) (born 1931), Japanese actor and voice actor