An interlocking mechanism includes an axial member reciprocating in a width direction of arrangement of first and second front doors by linking with an opening/closing operation of a side door. A stop member is provided rotatably and fixed in the width direction to the axial member. A restriction member presses the axial member toward the side door and having a pressing/urging member that urges the stop member in one of rotating directions. A pressing claw presses the stop member in the other of the rotating directions in a state where the second front door and the side door are closed. A restriction claw abuts on the stop member when the first front door is closed in a state where at least one of the side door and the second front door is open. An interlock switch is actuated by an actuator being inserted into the interlock switch.