The present invention can determine suitability/unsuitability of driving with high accuracy. This driving state determination device is provided with: an information acquisition unit that acquires information about the surrounding environment of a vehicle and the state of a driver of the vehicle; an information detection unit that detects change in the environment and change in the state from the information; a driving state determination unit that determines suitability/unsuitability of driving on the basis of the relationship between the change in the environment and the change in the state; and a signal output unit that outputs a signal corresponding to the determination result of suitability/unsuitability of driving.