To provide a differential sensor for detecting a differential pressure by measuring a displacement of a spool which is moved by the differential pressure, and excellent in small size, simple constitution, high precision, reliability, durability, and vibration proof etc.

The differential pressure sensor detects a differential pressure by measuring the displacement of the spool moved by the differential pressure. The sensor is provided with the spool equipped with a shock absorbing mechanism which absorbs the shock at the time of reaching the max. displacement and/or returning to a neutral position. The shock absorbing mechanism stops the spool by blocking a inflow fluid path before the max. displacement, and also stops the spool by a spring absorbing the shock by abutting the spool at the time of returning.