The present invention relate to a compound represented by the formula (I) or (II) ##STR00001## wherein ring A is an optionally substituted ring (the ring should not be pyrrolidine, piperidine and piperazine), ring B is an optionally substituted aromatic ring, ring D is an optionally substituted ring, R.sup.1 and R.sup.2 are each independently a hydrogen atom or a substituent, R.sup.3 is a hydrogen atom or a C.sub.1-6 alkyl group, or R.sup.3 is bonded to ring A to form a non-aromatic ring, ring Aa is an optionally substituted aromatic hydrocarbon, Y is CH or N, Ra.sup.1 is an optionally substituted hydrocarbon group, and Ra.sup.2 and Ra.sup.3 are each independently a hydrogen atom or a substituent, or a salt thereof. The present invention provides a compound having a DGAT inhibitory activity, which is useful for the treatment or amelioration of diseases or pathologies caused by high expression or high activation of DGAT.