To monitor the state of a driver from a driver's picture obtained by a camera.

A driver is successively photographed by a camera 10, and supplied to a facial direction detecting device 12. The facial direction detecting device 12 calculates a difference between the inputted driver's pictures, and segments a part whose difference value is a constant value or more as a facial position. The facial direction of the driver is detected based on the segmented facial picture and outputted to a looking-aside calculating part 14. The looking- aside calculating part 14 judges the presence or absence of the looking-aside of the driver from the facial direction and a steering angle or speed. Also, when the finite difference value can not be obtained, the time interval of the picture is increased, and the difference value is calculated gain. When the difference value can not be obtained even after the time interval of the picture is increased by more than a constant time, the looking-aside calculating part 14 judges that the consciousness of the driver is lowered.