1. A travel guidance device, comprising: a current position detection unit; and a controller that: acquires map data including a road network; acquires a position of a vehicle from the current position detection unit; acquires a planned travel route of the vehicle; based on the acquired position of the vehicle, the acquired planned travel route, and the acquired map data, determines whether there is a planned entry branch that the vehicle is projected to enter located ahead in an advancing direction of the vehicle; when the planned entry branch is located ahead of the vehicle, determines whether there is a no-lane-change zone specified in the road network between the vehicle and the planned entry branch based on the acquired map data; when the no-lane-change zone is located between the vehicle and the planned entry branch, sets guidance content related to a lane change of the vehicle based on a position of the no-lane-change zone; generates guidance using the set guidance content; and communicates the generated guidance to a user of the travel guidance device.