Abstract: Disclosed is a synthetic resin socket, which the LED module won't fall and can be securely held during the assembly operation to promote the efficiency of the assembly operation. The holder comprises an arm and a holding part formed at a front end of the arm. A holder accommodating room is formed at a bottom side of the socket main body. The holder protrudes from the inside of the holder accommodating room toward the lower surface of the socket main body for holding and temporarily setting the LED module. The arm of the holder is possible to be laterally elastically deformed, and as installation to an object to be installed, the objective presses against the holder and the arm provides resin elasticity to secure the hold status of the LED module, and the holder is elastically deformed toward the inside of the holder accommodating room to receive the LED module.