PURPOSE: To prevent a power section from being touched with a hand by a method wherein a shielding plate is interposed between a primary and a secondary power supply and locked by a locking lever, and a releasing lever acts on the both to release the shielding and the locking when a connector is connected.

CONSTITUTION: For instance, a copying machine 1 is provided, where a cassette bank unit 3 is moved inside a table 2 and an angular body 17 abuts against a locking lever 14 and presses it to rotate around a supporting axis. Then, the engagement of the locking lever 14 with the shielding plate 2 is released. When the cassette bank unit 3 is moved further inside the table 2, the angular body 17 pushes up the shielding plate 12 and rotates it in a clockwise direction. Then, a through-hole 11 is released from shielding, so that a female connector 8 is connected with a male connector 9 through the through-hole 11. When the cassette bank unit 3 is drawn out from the table 2, the shielding plate 12, which is pushed up by the angular body 17, pivots and descends by gravity to shut the through-hole 11, so that the female and the male connectors 8 and 9 are separated and shielded from each other.