A travel support device includes a mode planner. The mode planner selects one of a first mode, in which the state of charge of a battery is not maintained, and a second mode, in which the state of charge of the battery is maintained, based on a road load in each section on a travel route, thereby planning a travel mode. The mode planner selects from the travel route a first priority section, which is a section to be planned by giving priority to the first mode as a travel mode based on information on the travel route. The mode planner replans the travel mode when the vehicle is currently traveling at the first mode and also the remaining charge of the battery is less than the remaining charge of the battery necessary for traveling in the thus selected first priority section.