Optical device and direction display device

An optical device for displaying a condensing mark, comprising:

• a light source;
• and
• an optical element for condensing a light emitted from the light source into a shape of the condensing mark on an irradiated surface,
• wherein a deflection surface of the optical element is divided into a plurality of regions, the deflection surface being a surface for condensing the light, and
• lights emitted through the each regions on the deflection surface of the optical element form partial irradiation images on the irradiated surface corresponding to the regions on the deflection surface so that the partial irradiation images are combined into at least one condensing mark on the irradiated surface.