Agent for preventing/ameliorating obesity comprising methylidene hydrizide compound as active ingredient

The present invention provides a low-molecular inhibitor of GIP functions and, further, an agent for preventing/ameliorating obesity based on inhibition of GIP functions, which comprises, as an active ingredient, a compound represented by the following general formula (I): (wherein R1 represents hydrogen, halogen, a nitro group or a cyano group, R2 and R3 each represent hydrogen or halogen, hydrogen or a methoxy group, or both R2 and R3 may form an optionally substituted benzene or pyrrole ring, and A represents nitrogen or C-R4 whereupon R4 represents hydrogen, an optionally substituted C1 to C6 alkyl group, -OR7, -NR8R9, -NHCO-R10 or -SO2-R11 or may, together with R3, form an optionally substituted benzene or pyrrole ring, R7, R8 and R9 each represent hydrogen or an optionally substituted C1 to C6 alkyl group, R10 represents a C1 to C6 alkyl group or the like, and R1 represents an optionally substituted morpholyl group or the like) or a pharmaceutically acceptable salt thereof.