To provide a pressure sensor capable of preventing surely the surface of a pressure sensitive element from dewfall and keeping preferable pressure sensing accuracy without needing the disposition of a protective film or the like.

A diaphragm 62 is provided near the pressure receiving surface 62a with an electrode 66a (66b) and an auxiliary electrode 67 formed of a material having the heat transfer rate higher than that of the electrode 66a (66b). Further, a waterdrop catching groove 68 consisting of a fine groove is provided right below the auxiliary electrode 67. When the temperature of a pressure medium is abruptly lowered, dewfalls are selectively generated on the auxiliary electrode 67 and water drops made of the dewfalls are actively guided into the same waterdrop catching groove 68 and held therein by the capillary action of the waterdrop catching groove 68.