Optical device and direction display device

A direction display device installed in a vehicle, comprising:

• an optical device that displays a plurality of condensing marks which is a pattern indicating at least a travelling direction of the vehicle on a road surface around the vehicle;
• and
• a lamp controller that controls lighting or blinking of the optical device, wherein the lamp controller:
• acquires a detection signal from a state detection device, the state detection device being mounted on the vehicle and detecting a behavior of the vehicle and peripheral environmental information of the vehicle, and
• lights or blinks the optical device based on the detection signal;
• a plurality of linear partial irradiation images is combined into the plurality of condensing marks,
• the optical device arranges and displays the plurality of condensing marks side by side on a road where the vehicle is to enter in a direction in which the vehicle is to travel after entering the road, and the optical device displays the plurality of condensing marks in at least two different colors that appear to overlap each other to a viewer when the viewer is a certain distance from the vehicle, 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.