To switch a driving mode appropriately in response to a driver's intention by obtaining a sporty travel degree on the basis of lateral acceleration, steering angular velocity, accelerator opening and accelerator opening/closing speed, and switching from a two-wheel drive state to a four-wheel drive state when the sporty travel degree is larger than the specified value.

When switching a driving mode command from a two-wheel drive mode to a full-time four-wheel drive mode, a sporty degree (sport) is obtained on the basis of an expression, where K6, K7, K8, K9 are respectively specified coefficients, Gy is computed lateral acceleration, dθH/dt is a steering wheel angular velocity, θTH is throttle opening, and dθTH/dt is throttle opening/closing speed. Whether shift to the full-time four-wheel drive mode is possible is discriminated on the basis of the sporty degree (sport) as well as on the basis of vehicle speed V, propeller shaft rotation difference absolute value ΔVC, travel load resistance fV and a rough road degree (akuro). As a result, the actual driving mode is switched satisfactorily in response to a driver's intention.