PURPOSE: To simplify the amplification stage of a later stage, improve its reliability, and reduce its cost by providing a means for compensating the temperature influence of a diffusion resistance formed on a semiconductor compound sensor.

CONSTITUTION: A voltage signal Vref from a constant voltage power supply 108 is input to a temperature sensor 106 and an addition/subtraction circuit 110. Then, the output signal VRt from the sensor 106 is input to the circuit 110, thus enabling an output signal Vex of the circuit 110 to be in inverse characteristics of the temperature influence of the succeeding differential pressure sensor 102 and a static pressure sensor 104 by setting the signal processing details of the addition/subtraction circuit in advance and obtaining an output signal without temperature influence from a differential pressure sensor output terminal 112 and a static pressure sensor output terminal 114. Therefore, the differential pressure of the semiconductor compound sensor and the temperature influence of a pressure signal according to the temperature coefficient of a piezo resistance can be extremely reduced by a simple circuit and the amplification stage of the later stage can be simplified and made highly reliable.