[Object] To provide a GPR40 activating agent containing, as an active ingredient, a novel compound having a GPR40 agonist action, a salt of the compound, a solvate of the compound or the salt, or the like, particularly, an insulin secretagogue and a prophylactic and/or therapeutic agent against diabetes, obesity, or other diseases. [Means of Solving the Problem] A compound of Formula (I): (where p is 0 to 4； j is 0 to 2； k is 0 to 1； a ring A is an aryl group, a heterocyclic group, a cycroalkyl group, a cycroalkenyl group, a spirocyclic group； a ring B is an aryl group, a heteroaryl group； X is O or -NMR 7 -； and R 1 to R 7 and L are specific groups), a salt of the compound, or a solvate of the compound or the salt.
