Driver state detection device

A driver state detection device comprising:

• a driver monitor camera configured to capture the appearance of a driver of a vehicle to generate an image of the driver appearance;
• and
• a control device, wherein
• the control device is configured to:
• detect a facial orientation or a line-of-sight direction of the driver based on the image of the appearance;
• judge that the driver is driving distracted when the facial orientation or the line-of-sight direction of the driver is maintained for greater than or equal to a predetermined time period in a range at an outside from an allowable range allowed as the facial orientation or the line-of-sight direction of the driver;
• set the allowable range based on an operating parameter which is in a correlative relationship with steering operation of a steering wheel of the vehicle and a speed of the vehicle;
• set the allowable range to a first allowable range if the steering parameter is less than an expansion threshold value set in accordance with the speed of the vehicle;
• set the allowable range to a second allowable range broader than the first allowable range if the steering parameter is greater than or equal to the expansion threshold value;
• and
• decrease a magnitude of the expansion threshold value smaller as the speed of the vehicle increases.