An optical device for displaying a condensing mark includes a light source, and an optical element for condensing light emitted from the light source onto an irradiated surface. A lamp controller acquires a detection signal from a state detection device mounted on the vehicle and configured to detect a behavior of and peripheral environmental information of the vehicle, and light or blink the optical device. The optical device displays a plurality of condensing marks by arranging each of them side by side in at least the travelling direction of the vehicle on a lane orthogonal to a lane on which the vehicle exists, and one of the plurality of condensing marks to be displayed on a display region farthest from the vehicle is different in color from another one of the plurality of condensing marks to be displayed on a display region closest to the vehicle.