Recent automobiles are equipped with advanced safety technologies and sophisticated information processing systems for various purposes, such as advanced safety technology and information display to the driver. Driver monitoring has attracted considerable attention as an application of these components. There are two major applications for driver monitoring. One is in the field of “infotainment,” which improves usability by understanding the driver’s context and presenting the appropriate information. The other is in the field of advanced safety technology, which understands whether the driver is ready to drive and provides appropriate intervention.