Disclosed is a compound which is useful as an AMPK activator. A compound represented by formula: or its pharmaceutically acceptable salt, wherein X is substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted cycloalkenyl, or substituted or unsubstituted heterocyclyl； R 1 is hydrogen, halogen, cyano, nitro, carboxy, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted acyl, substituted or unsubstituted carbamoyl, substituted or unsubstituted alkylthio, substituted or unsubstituted alkylsulfinyl, substituted or unsubstituted alkylsulfonyl, or substituted or unsubstituted alkyloxycarbonyl； R 2 is halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted heterocyclyl, or the like； R 3 is halogen, hydroxy, cyano, nitro, carboxy, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted cycloalkenyl, substituted or unsubstituted heterocyclyl, or the like； and R 4 is hydrogen, halogen, hydroxy, cyano, nitro, carboxy, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, or the like.
