[Problems to be solved] A physical/chemical sensor that enables reduction of the size of the sensor and formation of arrays of the sensors is provided. The sensor can sense small change of surface stress and can measure mass of fixed specific substance. Also, a measuring method of the specific substance using the sensor is provided. [Means for solving problems] A physical/chemical sensor has a movable membrane (3) having a diaphragm structure provided to form a hollow section (2) between the movable membrane (3) and a light receiving surface of a light receiving element (1), a first piezoelectric membrane (4) that is provided on a front-side surface or a backside surface of the movable membrane (3) and that excites the movable membrane (3), and a second piezoelectric membrane (5) that is provided on the front-side surface or the backside surface of the movable membrane (3) and that senses a voltage caused by oscillation of the movable membrane (3). A measuring method using the physical/chemical sensor applies
