PURPOSE: To allow highly accurate measurement even of low pressure by fixing a temperature sensor, to be connected with a temperature compensation circuit, directly to an inner cylinder thereby allowing effective temperature compensation and enhancing safety against ambient temperature variation.

CONSTITUTION: When the temperature around a sensor body 2 varies during measurement, temperature of an inner cylinder 11 interposed between a filament 1 and the outer peripheral wall 2 of the sensor body varies slower than the ambient temperature variation. In case of such temperature variation as caused by ON/OFF operation of air-conditioner where temperature rise and drop are repeated normally, temperature variation of the inner cylinder 11 is smaller than the ambient temperature variation and thereby variation in the pointed value of Pirani gauge is suppressed. Furthermore, since a temperature sensor 12 detects temperature of the cylinder 11 directly, effective correction can be made under actual operating conditions. When a shielding board 14 is set, the fluctuation due to ambient temperature is suppressed in the pointed value of Pirani gauge which can thereby measure pressure as low as 10-3-10-2 pascal.