PURPOSE: To constitute the unit so that any of plural sub-units can be inserted into a slot of a connector of an input side and a connector of an output side of a main board by allowing the output side and the input side of the sub-unit of each interface part unit to take the same pin constitution.

CONSTITUTION: A unit of each interface part corresponding to each of plural requests to a device is constituted of plural sub-units 11, 12 in which connectors 111A, 111B of the pin constitution which can execute plug-in are attached to an input side A and an output side B. This unit 1 is constituted so as to be subjected to plug-in to a main board 2 to which the connectors 111A, 111B and the same number of connectors 112A, 112B of the slot constitution which can execute plug-in are attached. According to such a constitution, setting and a change of a user interface can be executed arbitrarily at every channel. Also, it is unnecessary for a developer of the device to design and manufacture many kinds of units, and there is such an effect as the development manhour and the development cost can be curtailed.