The present invention provides a hair growth agent having novel action mechanism and a hair growth composition containing the agent. Specifically, the present invention provides a novel hair growth composition containing one or more kinds of epsilon-N-(gamma-glutamyl)lysine or a salt thereof.本發明係提供以具新穎作用機制之育毛劑及含其為特徵之育毛用組成物。具體為提供以含1種或2種以上之ε-N-(γ-麩胺醯基)離胺酸或其鹽為特徵之新穎育毛用組成物。