Provided is a sensor capable of holding a sensing element at a position of good sensitivity without requiring filling of the case with resin. The sensor includes a sensing element, a case accommodating the sensing element and having a detecting face for the sensing element in an outer face thereof, a holder accommodated inside the case together with the sensing element and pressing the sensing element toward the detecting face and a cable electrically connected to the sensing element. At least one of the holder and the case includes a contact portion deformable by a pressing force generated when the sensing element is pressed toward the detecting face.