A reference value creating device includes processing circuitry configured to; vehicle-related information related to a vehicle; determine a road type of a road on which the vehicle is traveling on a basis of the acquired vehicle-related information; acquire feature amount information regarding a feature amount of an occupant of the vehicle calculated on a basis of a captured image including a range in which at least a face of the occupant of the vehicle is present; and create a reference value of the feature amount for estimating an alertness level of the occupant on a basis of the acquired feature amount information, and create, when the determined road type has changed, the reference value of the feature amount corresponding to the changed road type.