A parameter calculation part calculates an adaptive gain coefficient ‘k’ for the road surface conditions, based on frictional coefficient μ and a slip ratio λ from an acquisition part and a coefficient ‘b’ in a storage part. Subsequently, the parameter calculation part calculates an adaptive time constant τ by which the stability of traction control can be ensured, based on the gain coefficient ‘k’ and a coefficient ‘a’ within the storage part. Along with the calculated gain coefficient ‘k’ being set in a gain multiplication part, the calculated time constant τ is set in a filter part. According to these settings, model following control is executed by taking, as a reference model, an adhesion model in which the driving wheel does not slip. This enhances slip prevention performance while ensuring control stability, making stable travel possible while ensuring the required drive force in accordance with road surface state.