To provide a technique for preventing a wrong operation of an operation button.

A button unit 50 is, for example, a resin molding with a longitudinal direction upward and downward, and is formed to comprise a button base section 52, a button beam section 54, a button body 56, and a protrusion section 60. The button beam section 54 provided at a corner on a front right side of the button base section 52 is formed to extend backward to a predetermined length in a cantilevered manner. The button body 56 is formed rightward on a free end side of the button beam section 54. Also, the protrusion section 60 is formed to a predetermined length in a rib manner between the two button bodies 56 from a position at which the button beam section 54 is formed toward a projection direction of the button bodies 56. The button body 56 is not flexed unlike the button beam section 54. While the button unit 50 is provided inside a display section body 30, a tip portion of the protrusion section 60 comes into contact with a cabinet inner portion of a side face 32 of the display section body 30.