Head-up display device

A head-up display device that displays a virtual image of an imagery to be recognized by an occupant by projecting the imagery to a projection component in a mobile unit, the head-up display device comprising:

• a projector having a light source that emits a light and a liquid crystal panel on which the imagery is formed, the projector projecting the imagery by making the light emitted from the light source to be incident on the liquid crystal panel;
• an expansion optical system that expands and projects the imagery output from the projector on the projection component;
• an estimating part that estimates a relative position of the sun relative to the mobile unit based on a position of the mobile unit and a position of the sun;
• a determination part that determines whether the liquid crystal panel is to be protected based on a relation between the relative position of the sun estimated by the estimating part and a solid angle which represents a range in which a light of the sun is incident to the liquid crystal panel through the expansion optical system;
• and
• a light amount control part that decreases an amount of light incident to the liquid crystal panel when the determination part determines that the liquid crystal panel is to be protected compared with a case where the determination part determines that the liquid crystal panel is not to be protected.