An outer surface of a crosspiece portion of a leg body in a width direction is formed with a concave stepped portion that is recessed toward the inside of the crosspiece portion in the width direction. The concave stepped portion is formed over the entire length of the crosspiece portion. The concave stepped portion is provided with an attachment seat which an optional member is connected to. The concave stepped portion is blocked by a detachable cover member, so that it is possible to provide a desk device that enables the optional member to be added to the outer surface of the leg body if necessary without causing deterioration in the quality of external appearance.