A travel assist system, a travel assist method, and a computer program that prevent frequent corrections of a travel plan due to variations in congestion information are provided. Congestion information is acquired from a VICS center. The current state of a vehicle is acquired. It is determined whether or not the congestion status of an expected travel route for the vehicle has been varied from the congestion information using a criterion based on the state of the vehicle. In the case where it is determined that the congestion status of the expected travel route has been varied, the travel plan 48 is corrected using the congestion status after the variation.