A socket for an electrical part to prevent a bad electrical connection with a circuit by preventing a deformation of a tip of a contact pin. The contact pin of the present invention comprises one terminal contacts to a terminal of the electrical part and the other terminal contacts to the circuit. When a tip of the other terminal is pressed to a substrate under a state that first and second holes of first and second holding plates are shifted each other, an upper terminal of the held portion of the other terminal contacts to a lower surface of the second holding plate, and makes the second holding plate to separate from the first holding plate against a spring force of a urging member. At this time, the portion projecting from the lower surface of the first holding plate toward the substrate moves into the first hole.