PURPOSE: To easily attach an electrode supporting body to a socket main body and prevent detachment after attachment by forming a plurality of projected strips, which are extended from one end side to the other end sidein the axial direction of a socket main body, in the outer face of a cylindrical part of an electric bulb supporting body.

CONSTITUTION: A plurality of projected strips 30 extended from one side to the other side in an axial direction at the time when being attached to a socket main body 1 are formed at even distance mutually in the outer circumference of a cylindrical part 12 of an electric bulb supporting body 2 in which an electric bulb 3 is fitted. A prism part 13 at the tip of the electric bulb supporting body 2 is inserted in a square cylinder part 8 through a circular cylinder part 7 of a releasing part 4 of the socket main body 1. A column part 12 of the electric bulb supporting body 2 is fitted in the circular cylinder part 7 of the socket main body 1. At that time, only the projected strips 30 of the electric bulb supporting body 2 are brought into contact with the wall face of the circular cylindrical part 7 of the socket main body 1. The sliding resistance at the time of inserting the electric bulb supporting body in the socket main body 1 is lessened, so that both 2, 1 can be fitted each other smoothly.