Provided are an agent for imparting ceramide-like function,an agent for reinforcing skin barrier function, a moisturizing agent and a skin drug for external use.The agent for imparting ceramide-like function comprises as an effective ingredient a derivative of succinic acid diamide represented by the following formula (1):[wherein R1 and R2 each independently represents a hydroxyalkyl group of from 1 to 6 carbon atoms, R3 represents a group: —CH2CH2CH2CH2—R4 or a group: —CH2CH═CHCH2—R4 (wherein R4 represents an alkyl group of from 8 to 26 carbon atoms)].
