To obtain a prophylactic and/or therapeutic agent for PTP1B-mediated diseases.

PTP1B (protein tyrosine phosphatase 1B) inhibitor comprises a compound represented by formula (I) (wherein R1 is H or an alkyl; Q is an alkylene group which may have a substituent group or benzene, pyridine, pyrimidine, pyrazine or pyridazine ring which may have a substituent group; R2 is H, an alkyl group, an alkenyl group, an alkynyl group, Cyc1 or a substituted alkyl; G is an alkylene which may have a substituent group or an alkenylene which may have a substituent group; B ring is benzene, naphthalene or tetrahydronaphthalene which may have a substituent; E is a spacer having 1-8 number of atoms as a main chain; A is a cyclic group; (n) is 0 or 1; R3 is H or a substituent group; (m) is an integer of 1-7), its salt, solvate thereof or prodrug thereof as active ingredient.