A compound having the following formula (II) or its salt is used as an activator for PPAR .delta.: ##STR00001## [in which W.sup.3 is a nitrogen atom or CH; Z.sup.1 is an oxygen atom or a sulfur atom; each of R.sup.11 and R.sup.12 is a hydrogen atom, a halogen atom, a C.sub.1-C.sub.8 alkyl group, a C.sub.1-C.sub.8 alkoxy group, a C.sub.1-C.sub.8 alkyl group having a halogen substituent, or the like; each of R.sup.13 and R.sup.14 is a hydrogen atom or a C.sub.1-C.sub.8 alkyl group; A.sup.1 is pyrazole or thiophene which may have a substituent; and m is an integer of 2 to 4].