To achieve a mounting structure of an optional member which is capable of using a work space on a top plate much wider regardless of a structure of a leg body supporting the top plate and without providing a specific member under the top plate.

Furniture with a top plate includes an option mounting groove 1x for detachably mounting the optional member of a cup holder receiver 4 or the like in an end face 1a of the top plate 1. The top plate 1 includes: a core material positioned at the center part in the thickness direction; an upper top plate element 12 adjacent to the upper surface of the core material; and a lower top plate element 13 adjacent to the lower surface of the core material.