PURPOSE: To stimulate a driver directly and forcibly to prevent him from dozing by providing a heavy low-temperature reproducing driving unit of an audio reproducing apparatus on vehicle in a driver seat and oscillating this driving unit with an aperiodic frequency of an oscillator when the driver dozes.

CONSTITUTION: Driver's dozing is detected by a doze detecting part 28, and a controller 26 is operated by this detection signal. The controller 26 switches a switch 27 to the side of an oscillating block 24 and operates an oscillator 25 and an artificial random code pulse generator in the controller 26. When artificial random code pulse of the controller are outputted, the output of the oscillator 25 connected to the controller 26 becomes an aperiodic signal in accordance with the artificial random code, and this signal is amplified by a power amplifier 7 through the switch 27 to oscillate the driving unit 8, thus stimulating the driver to wake up him.