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
• each of the divided regions on the deflection surface irradiates partial irradiation images formed on the irradiated surface by lights emitted through each of the divided regions,
• each of the partial irradiation images formed on the irradiate surface have a linear shapes, each linear shape has a different inclination, and each linear shape is located at different positions on the irradiated surface, and
• the partial irradiation images become the condensing mark when combined with the partial irradiation images.