A part mounting mechanism includes a boss, and a resin clip adapted to be assembled to the boss. The resin clip includes holding pieces, elastic engagement pieces, and a connecting portion. The part mounting mechanism also includes projecting portions formed on facing inner surfaces of the connecting portion at predetermined intervals in a staggered fashion along a direction in which the boss is inserted. When the boss is inserted into the connecting portion, the projecting portions bite into the distal end portion of the boss.