Virtual image display device

A virtual image display device comprising:

• an image projection unit that selectively projects a first projection light linearly polarized in a first direction and a second projection light linearly polarized in a second direction orthogonal to the first direction to a windshield and that presents to a user a virtual image based on the first projection light or the second projection light reflected by the windshield;
• a reflected light measurement unit that measures an intensity of light incident from the windshield into the image projection unit along a light path in which the first projection light and the second projection light are projected;
• a determination unit that determines whether the user is wearing polarized sunglasses that shield a component linearly polarized in the first direction, based on a first light intensity measured by the reflected light measurement unit when the first projection light is projected, a second light intensity measured by the reflected light measurement unit when the second projection light is projected, and a background light intensity measured by the reflected light measurement unit in a non-display period in which neither the first projection light nor the second projection light is projected;
• and
• a display control unit that causes the image projection unit to project the first projection light when the determination unit determines that polarized sunglasses are not being worn and causes the image projection unit to project the second projection light when the determination unit determines that polarized sunglasses are being worn.