To provide a novel low-molecular-weight compound that inhibits the production of amyloid-β (Aβ ). A compound represented by the formula [I]: or a pharmacologically acceptable salt or ester thereof, wherein R1 and R2 are the same or different and each represent a substituent selected from the following Substituent Group a1; m represents an integer of 0 to 3; n represents an integer of 0 to 2; X1 represents a single bond or the like; X2 represents a single bond or the like; Ring A represents a five-membered aromatic heterocyclic group or the like which contains two or more nitrogen atoms and may have 1 to 3 substituents selected from the following Substituent Group b1; and Ring B represents a monocyclic or fused cyclic aromatic ring group such as the formula [2] which may have 1 to 3 substituents selected from the following Substituent Group c1, is effective as a therapeutic agent for a disease such as Alzheimer's disease. Substituent Group a1: a C1-6 alkyl group and the like Substituent Group b1: a C1-6 alkyl group and the like Substituent Group c1: an amino group and the like