To provide an IC socket not generating a crack or bend.

This IC socket comprises through hole group (15) penetrating from the top face to the undersurface of a case (3) and each probe pin (5) housed and supported in each through hole constituting the through hole group. A flange part (27) formed around the probe pin is mounted on a prepreg layer confronting in each through hole, the probe pin is pressed toward the prepreg layer while heating at a temperature higher than a hardening point of the prepreg layer and lower than a melting point of the case to weld the prepreg to the flange part. The prepreg layer is deformed to mitigate stress generated by pressing. By stress relaxation, the crack and the bend are effectively prevented.