A therapeutic or prophylactic agent for allergic dermatitis is disclosed. The therapeutic or prophylactic agent comprises as an effective ingredient a glycine derivative having a specific structure or a pharmaceutically acceptable salt thereof, for example, the below-described compound [(E)-2-(2,6-dichlorobenzamido)-5-[4-(isopropyl-pyrimidin-2-ylamino)phenyl]pent-4-enoic acid]. The therapeutic or prophylactic agent for allergic dermatitis according to the present invention has high therapeutic or prophylactic effect.
