According to the present invention there is provided a highly reliable position sensor capable of preventing the entry of foreign matters such as water and dust from the exterior into a receptacle chamber formed within a housing. Formed in the housing are a mounting opening to be mounted in a sealed state to a throttle body and a receptacle chamber having an opening. The receptacle chamber and the mounting opening are partitioned from each other by a partition wall. A sensor body is mounted into the receptacle chamber and the opening of the chamber is covered with a cover, then a clearance formed between the opening and the cover is filled and sealed with a thermosetting resin such as an epoxy resin. A communication hole for communication between the receptacle chamber and the mounting opening is formed through an operating shaft which is rotating a sliding-element receiver of the sensor body. While the thermosetting resin is heated, the air expanded in the receptacle chamber is allowed to escape through the communication hole to the exterior. After a throttle position sensor as the position sensor has been attached to the throttle body, the communication hole formed in the operating shaft is shut off from the exterior by the mounting surface for the throttle body.