PURPOSE: To make it possible to fix a base to a bulb securely, as well as to cover the connection of bulb members and to improve the appearance, by furnishing gearing projections at the base projecting to be engaged to the connections of the bulb.

CONSTITUTION: At the inside of a bulb 11, bulb members 13 and 14, which have a bend bending in U-shape at each top, are arranged parallel on the horizontal surface, and the neighboring inside ends of the both bulb members 13 and 14 are linked and connected airtight each other by a connection 15,to form in approximately W-shape. At the both ends of the bulb 11, filaments are furnished, and at an electrical connection 26 at the lower side of the base 12, four connection pins 27, which are connected to the filaments furnished at the both ends of the bulb 11 through lead wires, are projected. The connection 15 of the bulb members 13 and 14 is geared with gearing projections 24 and 25 of the base 12 from both sides, fixing the base 12 to the bulb 11. Therefore, the base is fixed to the bulb securely to prevent its removal, and covered by the gearing projections to improve the apperance.