A risk potential calculating device for a vehicle, comprises a state recognition device that detects vehicle conditions of a subject vehicle and a traveling environment for vehicle surroundings; and a risk potential calculator that calculates a risk potential for the vehicle surroundings based on detection results of the state recognition device. The risk potential calculator calculates the risk potential by respectively calculating a first risk potential expressing a risk in a case where driving conditions of the subject vehicle are in a steady state and a second risk potential expressing a risk for a case where driving conditions of the subject vehicle are in a transient state, and adding the first risk potential weighted by a first coefficient and the second risk potential weighted by the second coefficient.