A mount mechanism used to mount an accessory gear box on an engine case in an aircraft engine, includes a pair of first brackets apart from each other in a circumferential direction of the engine case; the pair of first brackets being connected to each other via the link, both end portions of the link being coupled to the pair of first brackets by a pair of first pins, respectively; an annular anti-vibration element penetrated by each of the pair of first pins, the annular anti-vibration element being retained by at least one of each of the pair of first brackets and the end portion of the link; and a second bracket fastened to the other of the engine case and the accessory gear box, the second bracket box being coupled to the link by a second pin at a location between the pair of first brackets.