An operating rod is subjected to a surface hardening heat treatment without a post finishing process which enhances a responsiveness of the operating rod by preventing powders from being attracted to a sliding surface of the operating rod. The capacitive control valve includes a solenoid rod portion communicating with a moveable core of the solenoid portion, an operating rod connected with the solenoid rod portion, the operating rod including a valve body used for opening or closing a control fluid passage hole, and a fixed core arranged opposite relative to the moveable core. The fixed core includes a guide hole defined therein which guides the operating rod through the guide hole in a freely moveable manner, the operating rod extending longitudinally through an internal bore. The operating rod being subjected to surface hardening treatment at a relatively low temperature that does not exceed 500° C.