A peripheral information obtaining unit, a road information obtaining unit, and a communication unit which are included in a driving environment obtaining unit obtain information indicating a current state of a drive environment. A driver information obtaining unit and a vehicle information obtaining unit which are included in a driving state obtaining unit obtain information indicating a driving state of a current driver. A display controller controls at least one of a display position and a display timing of a guidance sign to be displayed on a display unit, based on at least one of the pieces of information which are output from the driving environment obtaining unit, the driving state obtaining unit, and a route guiding unit.