A member assembly includes a first member and a second member joined to the first member. The first member includes an engagement piece provided with an engaged portion. The second member includes an engaging portion to be engaged relative to the engaged portion, and a hook allowing a tip of the engagement piece to be inserted therein. The hook permits the engagement piece to move in a direction intersecting with an inserting direction of the engagement piece. The engaging portion permits the engaged portion to move by a certain distance in the direction intersecting with the inserting direction of the engagement piece.