The present invention provides an induction heating device for a fuel cell system, which can rapidly heat coolant during cold start-up, control the power consumption depending on the voltage of a fuel cell stack, and ensure the insulation resistance by separating a heating unit, which is in contact with the coolant, from the outside. That is, the present invention provides an induction heating device for a fuel cell system, in which an insulating housing is provided in a coolant circulation line, a heater for heating coolant is provided in the housing, and a high frequency controller for controlling the power consumption of the heater is provided at the outside of the housing such that the coolant can be rapidly heated during cold start-up, precisely control the power consumption depending of the voltage of a fuel cell stack, and improve the insulation performance by separating the heater as a heating unit, which is in contact with the coolant, and the high frequency controller and a coil as a power unit with respect to the insulating housing.