PURPOSE: To provide a topboard of a desk or the like excellent in practicability by enabling the selection of diversified combination arrays securing matching property between topboards.

CONSTITUTION: A topboard 1 has a roughly trapezoidal main flat plate 2 in the plane. The upper side 4, the left side 5 and the right side 6 of the main flat plate 2 are roughly linear in the plane and the lower side 7 thereof is sunk gently being curved almost parallel with the upper side 4. The left side 5 of the main flat plate is at the right angle to the upper side 4 and the right side 6 at the angle of about 135° to the upper side 4 in almost the same length as it. A sub flat plate 3 roughly triangular in the plane is formed on the lower side 7 of the main flat plate integrally and the right side 8 of the sub flat plate connected to the right side 6 of the main flat plate is made linear almost at the right angle to the right side 6 of the main flat plate. The left side 9 of the sub flat plate is bulged gently being curved almost parallel with the right side 6 of the main flat plate.