A running control device of a vehicle includes an engine with a plurality of cylinders, and a clutch connecting/disconnecting a power transmission path between the engine and wheels, the running control device of a vehicle performing during an inertia running mode a neutral inertia running mode performed with the power transmission path between the engine and the wheels disconnected while the engine is kept operated, and a cylinder resting inertia running mode performed by resting at least a part of the cylinders of the engine while the power transmission path between the engine and the wheels is connected, the running control device of a vehicle increasing an operation region of performing the neutral inertia running mode in an operation region of performing the inertia running mode when idle learning performed in an idle operation state of the engine is incomplete, as compared to after completion of the idle learning.