A touch panel device includes a display unit, a detector, and a controller. The display unit displays, on a display screen, a nautical chart (map), and a touch panel device symbol indicating a position of the ship on the nautical chart. The detector detects rotating operation that is touch operation of rotating around the touch panel device symbol over a predetermined angle while touching the touch panel device symbol. When the detector detects the rotating operation, the controller switches a display mode to a different display mode in which a reference azimuth defining a displaying orientation of the nautical chart is different.