PURPOSE: To improve the precision of pressure measuring operation by composing part of an airtight container of a movable deforming member, incorporating a moisture-sensitive element and also sealing vapor, and detecting variation in the electric resistance value of a temperature-sensitive element with the pressure in the airtight container.

CONSTITUTION: The temperature-sensitive element 2 has a moisture-sensitive film formed, for example, styrene sodium sulfonate, and a couple of comb-shaped electrodes are arranged. Then, the temperature-sensitive element 2 is arranged in the airtight container formed by covering a stem with a cylindrical cap 5 having a deformed cover 4 of natural rubber, etc., atop and vapor is sealed. When the ambinet pressure varies, the deforming cover 4 deforms to cause variation in the vapor pressure in the airtight container, and the amount of water absorption of the temperature-sensitive element 2 varies to vary the electric resistance value of the temperature-sensitive element 2, so variation in this electric resistance value is detected to measure the pressure at the atmosphere of the pressure sensor accurately.