Disclosed herein are a filament lamp for heating a disk-shaped workpiece in such a way that the filament lamp rotates relative to the workpiece and radiates light thereonto. Further, the present invention provides a structure that enables the filament lamps to uniformly heat the workpiece even with respect to the radial direction of the workpiece. For this, the filament lamp includes an arc-shaped emitting part which extends in a circumferential direction of the relative rotation, and an auxiliary emitting part which is disposed inside a circle extending along the arc-shaped emitting part and extends from the arc-shaped emitting part in a direction crossing the circle. In addition, the present invention is configured such that areas of the workpiece that correspond to spaces between the arc-shaped emitting parts of the adjacent filament lamps pass just below the corresponding auxiliary emitting parts.