To provide an in-vehicle theft watch machine capable of keeping watch for movements of persons outside and near the vehicle and intrusion into the vehicle by securely distinguishing the outside and the inside of the vehicle.

A microwave sensor transmits a microwave signal to watch the inside of the vehicle and the periphery outside the vehicle as a detection range by a micro wave antenna 11 and receives a reflected microwave signal so as to detect a moving body by the frequency shift of the received microwave signal. An ultrasonic sensor transmits an ultrasonic signal into the vehicle by a transmitter receiver 21 and receives a reflected ultrasonic signal so as to detect the moving body by the frequency shift of the received ultrasonic signal. Each of a circuit detecting the moving body by the frequency shift in the both sensors is composed of a shared circuit 3. The signal processing circuit 4 monitors a detection signal of the microwave sensor and a detection signal of the ultrasonic sensor outputted from the shared circuit 3 and a notification is made by an alarm 5 based on the detection signals.