A lid opening/closing mechanism includes an arm, an arc-shaped gear, a first fixed gear, a damper, a second fixed gear, and a tension spring. The arm is disposed integrally to project from the lid to swing about a swing center as the lid opens and closes. The arc-shaped gear is formed in the arm. The first fixed gear is disposed in the body, and meshes with the arc-shaped gear. The damper is disposed in the arm, and includes a damper gear. The second fixed gear is disposed in the body, is formed along a movement locus of the damper moving as the lid moves to open and close, and meshes with the damper gear. The tension spring is disposed between the body and the arc-shaped gear to urge the lid in an opening direction.