To determine whether a driver's state is suitable state for driving.
A vehicle-mounted device 10 includes: a traveling support control unit 30 that senses that the driver is provided with guidance regarding the driving operation; a line-of-sight detection unit 32 that detects the direction of a driver's line-of-sight; a condition determination unit 33 that determines whether a gaze condition is satisfied, the gaze condition including: that, with respect to a preset gaze direction, the driver's line-of-sight faces the gaze direction until a first reference time elapses from when guidance is sensed; and that time during which the driver's line-of-sight faces the gaze direction is equal to or longer than a second reference time; and a driver state determination unit 34 that determines whether the driver is in a state of being able to drive based on the determination result of the condition determination unit 33.