Contact pins are provided to a socket main body for accommodating an IC package so as to be in contact with connection terminals of the IC package accommodated in the socket main body. Each contact pin includes a conductive substrate and multiple layers laminated on the surface of the substrate, including: an underlying layer formed on the substrate by Ni plating; a first surface layer formed on the underlying layer by Pd—Ni alloy plating; a second surface layer formed on the first surface layer by Ni plating, thus allowing Sn from the corresponding connection terminal to diffuse into the second surface layer at a rate lower than into a conventional plated Ag layer; and an outermost surface layer formed on the second surface layer by Au plating to serve as an electrical contact layer.