A sensor control apparatus (2) of a gas detection system (1) includes a first low-pass filter (46), a second low-pass filter (48), and a multiplexer (50) so as to provide different time constants for detection of a sensor output signal Vs1 and for detection of a response signal Vs2. When the sensor output signal Vs1 is detected, a signal whose frequency band is the same as that of Vs1 is input to the analog-to-digital conversion section (31) through the first low-pass filter (46). Therefore, the detection accuracy of Vs1 is increased. When Vs2 is detected, a signal whose frequency band is the same as that of Vs2 is input to the analog-to-digital conversion section (31) through the second low-pass filter (48).