A compound represented by the following general formula (I) or a salt thereof, or a solvate thereof: (wherein R1, R2, R3, R4 and R5 are the same or different, and represent hydrogen atom, a halogen atom, a lower alkyl group etc., R6, R7 and R8 are the same or different, and represent hydrogen atom, a halogen atom, a lower alkyl group etc., R9 and R10 are the same or different, and represent hydrogen atom, a lower alkyl group, a (lower cycloalkyl)(lower alkyl) group etc., and R11 represents hydrogen atom, a halogen atom, a lower alkoxy group, a (lower alkyl)thio(lower alkoxy) group, a (lower alkyl)sulfinyl(lower alkoxy) group, a (lower alkyl)sulfonyl(lower alkoxy) group etc.), which has potent inhibitory activity on CETP.