To provide a novel pressure sensor that is superior in corrosion resistance and inexpensive capable of extending a range of pressure sensing and adding a detecting function other than pressure.

A pressure sensor 10 is constituted in such a manner that a recess 11t having a flat bottom face is formed at one surface Sa of a silicon substrate 11, a diaphragm 12 deformable by pressure is arranged so as to cover the recess 11t, a closed space Vc is formed with the recess 11t and the diaphragm 12, gas is enclosed in the closed space Vc, a heating element H and temperature measuring elements M1, M2 are arranged at the bottom face side of the recess 11t, an electrode 13 which is connected to the heating element H and the temperature measuring elements M1, M2 is arranged at the other surface Sb of the silicon substrate 11. The pressure sensor senses pressure applied to the diaphragm 12 from temperature changes of the temperature measuring elements M1, M2 with the gas heated by the heating element H as a medium.