A novel therapeutic agent for hyperlipidemia, which is an ester compound represented by the formula (1'') ##STR00001## (wherein R.sup.1 and R.sup.2 are each hydrogen atom or optionally substituted aryl, etc.; X is --COO-- or --CON(R.sup.10)--; R.sup.3 and R.sup.4 are each hydrogen atom, C.sub.1-C.sub.6alkyl or C.sub.1-C.sub.6alkoxy, etc.; R.sup.5, R.sup.6 and R.sup.7 are each hydrogen atom, C.sub.1-C.sub.6 alkyl or C.sub.1-C.sub.6 alkoxy, etc.; R.sup.8 and R.sup.9 are each independently hydrogen atom, C.sub.1-C.sub.6alkyl, --CON(R.sup.18)(R.sup.19) or --COO(R.sup.20), etc.; ring A, ring B and ring C are each independently aryl or heterocycle residue, etc.; Alk.sup.1 and Alk.sup.2 are each independently alkanediyl, etc.; l and m are each an integer of 0 or 1 to 3) or a prodrug thereof, or a pharmaceutically acceptable salt of either. The therapeutic agent selectively inhibits MTP in the small intestine, thus causes no such side effect as a fatty liver.