To inexpensively prevent detachment of a lock pin in such a state that a lid member and a main body are closed.

For example, in a light control operation table for controlling a large number of spotlights, a lid member 1 having a fader, a switch or the like arranged thereto is provided in a main body 2 housing a circuit board loaded with a microcomputer or the like in an openable and closable manner by a hinge mechanism (h) such as a hinge or the like to be connected to the main body 2 by a plurality of extensible stays 3, 4 and, in such a state that the stays 3, 4 are extended, a lock pin 5 is inserted in the hole 6 of the stay 4 to hold the lid member to a state opened from the main body 2. In this housing, a housing hole 7 in which the lock pin 5 is inserted is provided in the main body 2 and the lock pin 5 inserted in the housing hole 7 is made impossible to get out by the stay 4 in such a state that the lid member 1 and the main body 5 are closed.