To provide a top plate of a kotatsu made of easily recycleable material, having freedom for setting the weight while keeping strength.

Raised edge parts 32, 32a and ribs 33, 33a are respectively integrally projected on the peripheral edge part and surface of a horizontal plate 31 made of a synthetic resin, the central sides of the ribs 33, 33a are lowered to form placing parts 34, 34a, which is taken as a base plate core 3, metal weight plates 4, 4a are placed on the placing parts 34, 34a to constitute an inner member 2. The surface of the inner member 2 is provided with decorative plates 5, 5a and the side is provided with an edge band plate 6, whereby as the principal member of the top plate 1, used is regenerated synthetic resin material, and the top plate can be set to a desired (optimum) weight while required strength is secured.