A compound having the following formula or its salt is used as an activator for PPAR: ##STR00001## in which W.sup.2 represents a bond, C(.dbd.O) or CH.sub.2; Z.sup.2 represents an oxygen or sulfur atom; R.sup.21, R.sup.22 and R.sup.23 independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a halogen atom, an alkyl group having 1 to 8 carbon atoms which is substituted with a halogen atom or the like; and R.sup.24 and R.sup.25 independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an alkyl group having 1 to 8 carbon atoms which is substituted with a halogen atom.