A pair of terminal portions of a bus bar (i.e. a terminal clamp) includes spring portions each of which is arranged to exert a pushing force in a direction of sandwiching a base portion of a bulb, and contact portions each provided at a tip portion of the spring portion. A housing (i.e. a socket body) includes regulation portions located on opposite side of the terminal portions and arranged to abut on the terminal portions from opposite side of the base portion to regulate elastic deformation amount of the spring portions to be within a predetermined value.