To improve the reliability of the physical state measurement data of a vehicle driver, to store the measurement data for respective drivers and traveling condition sections and to retrieve the measurement data of a previous time.

The driver presses the touch panel switch of a driver specifying device 1 and inputs driver information and a traveling condition detector 2 prepares and outputs a section table composed of a time band section, a view field section, an average car speed section and a road kind section. In an electrocardiogram signal detector 3, the electrocardiogram signals of the driver are obtained from an electrode on a steering. In a pulsating interval variance calculation circuit 4, defective data including detection errors and noise are eliminated, a pulsating interval variance and an average heart rate are calculated from the electrocardiogram signals and a centroid position on a two-dimensional plane is obtained. In a mental fatigue level judgement circuit 5, the measured centroid position and the centroid position of the previous time in the same section of the same driver stored in a memory 6 are compared and a mental fatigue level is judged. The measured centroid position is stored in the memory 6 along with the driver information and the section table.