A serum cholesterol lowing agent or a preventive or therapeutile agent for atherosclerosis, which each comprises a combination of a compound represented by the following general formula (I) or pharmaceutical acceptable salts thereof with a cholesterol biosynthesis inhibitor and/or a fibrate type cholesterol lowing agent. (I) (b) (a) [In the formula, A1, A2, A3 and A4 each is hydrogen, a group represented by the formula (b), or a group represented by the formula (a), provided that at least one of these is a group represented by the formula (a); A2 is C1-5 alkyl etc; and n. p, q and r each is an integer of 0, 1 or 2.