PURPOSE: To make unnecessary the work of changing lamp holders to a head by making the wind-up portion of a straight bulb opposite to either one of plural lamp holders when the straight bulb is wound into a circle, and making the wind-up portion supported by the lamp holder.

CONSTITUTION: A head 12 is provided with a lamp holder 27 supporting the wind-up portion 16c of a bulb 16a for 32W and a lamp holder 28 supporting the wind-up portion 16d of a bulb 16b for 40W, both of which holders 27, 28 are arranged in the direction of the respective pipe axes of the wind-up portions 16c, 16d. Even if the winding inside diameters R1, R2 of the bulbs 16a, 16b are varied, the chuck arm 33a, 42a of either the lamp holder 27 or 28 is opposite to and fits with the wind-up portion 16c, 16d of the bulb 16a, 16b so that the wind-up portion 16c, 16d can be supported. Therefore the work of changing lamp holders 27, 28 to the head 11 each time wattage is changed is not needed at all.