An automotive burglar alarm unit has an intrusion or equivalent security sensor. The burglar alarm unit can operate in an alarm set state for generating alarm, with a security sensor OFF mode for invalidating a signal of the security sensor. A user can use a portable phone to transmit a sensor ON signal via an information center. When the burglar alarm unit receives the sensor ON signal, the burglar alarm unit shifts into an alarm set state of security sensor ON mode so that the burglar alarm unit can generate alarm in response to a signal of the security sensor. Furthermore, the user can transmit a sensor OFF signal. In response to the sensor OFF signal, the burglar alarm unit shifts into an alarm set state of security sensor OFF mode so that no alarm is generated based on the signal of the security sensor.