To provide a top plate whose edge is effectively decorated by using a metal extruded shape member.

The extruded shape member has a top plate material 11 having a groove 11e along the edge 11c is mutually fixed with an extruded shape having a hook 12a to be inserted into the groove 11e, a cover 12b covering the top plate 11a' of the top plate material 11 from the groove 11e to the edge 11c, a suspension board 12c covering the side edge 11d while extending downward, and an attachment 12d protruding backward from the suspension board 12c, and the members are mutually fastened by inserting a reinforcing material or through a reinforcing material 13 attached to the top plate material.