For facilitating an electrical connection of a conductive connection pin (7) to a conductive contact (11) held to a base insulator (13), an electrical connector includes a preload pin (23) which is for carrying out beforehand displacement of a contact portion (21) of the conductive contact at a first position. The preload pin is held to a slider (19) which is placed between the base insulator and a cover insulator (17) and which is movable in a predetermined direction. The cover insulator and the slider have guide and elongated holes (15, 25), respectively, for passing the connection pin therethrough. The elongated hole is greater than the connection pin in a size of the predetermined direction. Therefore, it is possible without movement of the connection pin to move the preload pin in the predetermined direction to a second position at which the preload pin does not carry out the displacement of the contact portion.