Abstract: A driving assistance device 1 is provided with: three or more detection units 5a to 5d which are configured to detect a likely-to-be-dozing state in which likelihood that a driver of a vehicle is dozing is high by different indices and at prescribed intervals; a state determination unit 34 which determines that the driver is in a dozing state when the likely-to-be-dozing state is detected by at least two of the detection units; and a warning control unit 36 which causes a warning device 6 to issue a warning when the state determination unit 34 determines that the driver is in the dozing state.