To provide a switch device securing safety using a mechanical safety control means without any sensor for electrically detecting the rotation angle of a steering wheel and outputting effective bioinformation alone of a driver.

This physiological data extraction device which has the steering wheel operated by the driver for controlling the traveling direction of a traveling car and a vital sensor provided on the steering wheel for detecting the physiological data of the driver with its coming into contact with the palm of the driver, and extracts the physiological data of the driver based on the detection output from the vital sensor; is further provided with a moving member moving interlocked with the rotation of the steering wheel, and a switch means, when the moving member moves a prescribed distance or more, mechanically opening a switch by the movement of the moving member; and is characterized in, when the switch is opened by the switch means, non-extracting the detection output from the vital sensor as the physiological data.