A fault simulation system that has a simulation unit comprising an ECU model including an element fault model made to have a fault by a time setting or external command and all or a portion of a sensor model, actuator model, vehicle model, and driver model and can evaluate vehicle behavior at the time of an element fault according to driving operation based on a set travel scenario, wherein the passage time, vehicle behavior, driving operation, and the like, at each point on a course are determined through non-fault simulation and on the basis of that information, an element fault is inserted according to a fault time setting or fault command for the element fault model.