The head-up display device projects a virtual image and includes: an image processor that processes an image to be displayed as a virtual image; an image display that projects the processed image; and a display controller that controls the displaying of the image display. The image display includes: a projector that projects an image; a diffusion plate that forms the image projected by the projector; and a lens that guides the image formed by the diffusion plate. The diffusion plate is constituted by a plurality of functional liquid crystal films that are located at different distances from the lens. The display controller is configured such that, by controlling a transmissive state and a white state of each functional liquid crystal film, the position and distance for displaying the virtual image can be changed.