An inter-vehicle distance maintenance supporting system for a host vehicle can include an obstacle detector that detects the obstacle present ahead of the host vehicle, an inter-vehicle distance detector that detects the inter-vehicle distance between the host vehicle and the obstacle, a confidence factor computing device that computes the confidence factor for taking the obstacle as a preceding vehicle ahead of the host vehicle based on the state of the obstacle detected by the obstacle detector, a confidence factor correcting part that corrects the confidence factor based on the relative-position relationship between the host vehicle and the obstacle, and a reaction force controller that applies a reaction force on the accelerator pedal based on the inter-vehicle distance and the confidence factor.