Pressure sensor with diaphragm for detecting pressure

A pressure sensor has a diaphragm with a first layer and a second layer, a pressure transmitting member being in contact with the second layer, and a sensing element. The diaphragm is deformable in response to a pressure applied on a front surface of the first layer. The transmitting member transmits this pressure to the sensing element. The sensing element detects the pressure. A heat applied to the diaphragm induces the layers to be shifted toward the transmitting member or the opposite side of the transmitting member due to a shape of the diaphragm. The layers of the diaphragm have thermal expansion coefficients differing from each other. A thermal deformation of the layers caused by the thermal expansion difference between the layers cancels out the thermal deformation of the layers originated in the shape of the diaphragm.