The present invention provides a compound represented by the following formula (1); wherein R1 is an aryl group etc.; R2 is —CO—NH— etc.; R3 is a methyl group having an aromatic group or a cycloalkyl group; R4 is a hydrogen atom etc.; R5 is a methyl group having an aromatic group; and R6 is an amino group or an N-alkyl substituted amino group, having a low-molecular weight and a superior GPR54 agonist activity, and a pharmaceutical composition containing the compound.