PURPOSE: To make costless, moreover reduce the danger of damage due to discharge etc., and made excellent appearance by providing the interface substrate projecting toward the outward of an end connection when a door is opened on the inner surface of the door, and connecting the interface connector at an optional equipment side on the substrate.

CONSTITUTION: An end connection 22 is provided at the main body side of an office automation equipment and also the door 23 opening/closing the end connection 22 is hinged, the interface substrate 25 projecting toward the outward of an end connection when the door 23 is opened is provided on the inner surface of the door 23, and the interface connector 29 at the main body side of the office automation equipment and the interface connector 31 at an optional equipment side are connected on the substrate 25. This enables the interface connector to be completely housed in the inside of the main body side, consequently excellent appearance is obtained, and since a costless connector for internal connection serves the purpose, cost down is made, moreover the occurrence of static electricity discharge in the connector terminal part is reduced, and the danger of discharge breakdown is also lowered.