PROBLEM TO BE SOLVED : To provide a novel compound useful as a medicine which has excellent Aβ aggregation inhibitory activity.SOLUTION : There is provided an imidazole compound represented by the formula (1) or a salt thereof. (A to C each independently represent H or C; X1 and X2 each independently represent -CH2-, -O- or -S-; R1 and R2 each independently represent a substituted/unsubstituted aromatic hydrocarbon group; R3 represents H or a straight/branched-chain alkyl group; R4 represents a straight/branched-chain alkyl group or a cyclic alkyl group; R3 and R4 may form a saturated heterocycle together with the adjacent nitrogen atom; R5 represents a straight/branched-chain alkyl group or a cyclic alkyl group; either one of R6 and R7 represents H or an alkyl group; one double bond exists in dashed line in an imidazole ring.)SELECTED DRAWING : NoneCOPYRIGHT : (C)2019, JPO&INPIT