A worktable device is disposed inside a film formation process container for a semiconductor process. The worktable device includes a worktable including a top surface to place a target substrate thereon, and a side surface extending downward from the top surface, and a heater disposed in the worktable and configured to heat the substrate through the top surface. A CVD pre-coat layer covers the top surface and the side surface of the worktable. The pre-coat layer has a thickness not less than a thickness which substantially saturates the amount of radiant heat originating from heating of the heater and radiated from the top surface and the side surface of the worktable.