To provide a navigation system for a vehicle for properly avoiding a state performing sudden lane modification in response to a route guide.

A navigation ECU constituting the navigation system determines a lane on a road positioned at a time point when the vehicle approaches up to 100 m to a branch point when guide performing right turning at the branch point on a route is planned by a display device and a speaker. The navigation ECU stops the guide when it determines that the determined lane is an improper lane in the case that the vehicle turns right at the branch point and retrieves the guide route up to a destination again.