A running control device of a vehicle includes an engine, a clutch separating the engine and wheels, and a torque converter with a lockup clutch transmitting power of the engine toward the wheels, the running control device of a vehicle is configured to execute a neutral inertia running mode that is an inertia running mode performed while the engine and the wheels are separated and a cylinder resting inertia running mode performed by stopping operation in at least some of cylinders of the engine while the engine and the wheels are coupled, the lockup clutch has a weak engagement force while the neutral inertia running mode is performed as compared to while the cylinder resting inertia running mode is performed.