Sensor control unit and gas detection apparatus

A sensor control circuit unit connected to a gas sensor which outputs a detection signal changing in accordance with concentration of a specific component, the sensor control circuit unit comprising a circuit board which has opposite sides facing in parallel with each other and which carries a signal detection circuit for receiving the detection signal, a power supply circuit for supplying a drive voltage to circuit elements mounted on the circuit board, and a heater circuit for controlling a heater which heats the sensor, wherein

• the power supply circuit and the heater circuit are mounted on one side of the circuit board toward one of the opposite sides, and the signal detection circuit is mounted in a mounting area on the other side of the circuit board toward the other of the opposite sides, the mounting area being different from a mounting area of the power supply circuit and the heater circuit;
• and
• a ground conductor connected to a ground is continuously formed on a surface of the circuit board on which the signal detection circuit is mounted such that the ground conductor extends along at least the other of the opposite sides.