A compound represented by the formula [I]: [wherein R1 and R2 are the same or different and each represents C1-6 alkyl, C3-8 cycloalkyl, et al; R3a, R3b, and R4 are the same or different and each represents hydrogen, C1-6 alkyl, et al; X represents —N—, —CH—, et al; Y1 represents a single bond, C1-3 alkylene, et al; Y2 represents C1-4 alkylene, oxy(C1-4 alkylene), et al; Ar1 represents a monocyclic aromatic carbocyclic group, monocyclic aromatic heterocyclic group, et al; and Ar2 represents a 5- or 6-membered aromatic carbocyclic group, aromatic heterocyclic group, et al]. This compound functions as a melanin-concentrating hormone receptor antagonist and is useful as, e.g., a therapeutic agent for obesity, et al.