To provide a fixing structure easy for putting both of a mouse table into a horizontal use state or perpendicular housing state.

The base surface of a mouse table 1 for housing the main table of a computer table by bending its edge is provided with a moving piece 3 which maintains the mouse table 1 on approximately the same plane as the plane of the main table 2 on the bottom surface of the mouse table 1. This moving piece is disposed movably from the mouse table toward the main table so that the moving piece moves to the mouse table 1 side when the end of on the main table side of the moving piece 3 bends the mouse table 1.