A physical quantity sensor includes two substrates and a movable electrode that is disposed between the two substrates and is bonded to the two substrates. In the physical quantity sensor, the movable electrode has an elastically deformable diaphragm and one of the two substrates is an electrode substrate having a detection electrode on a detection surface opposite to the diaphragm to detect capacitance between the diaphragm and the detection electrode. In the physical quantity sensor, in a range between a room temperature and a bonding temperature when the two substrates and the movable electrode are bonded, coefficients of thermal expansion of the two substrates are smaller than that of the movable electrode and in a temperature range where the physical quantity sensor is used, a coefficient of thermal expansion of the movable electrode is between a first and second substrates.