Heads-up display device

A head-up display device that reflects and enlarges a displayed primary display image by a curved mirror to allow an observer to visually recognize the primary display image as a virtual image, the head-up display device comprising:

• a virtual-image-position changer configured to change a distance between the observer and the virtual image;
• and
• a display-size changer configured to change a display size of the primary display image,
• wherein the following conditional expression (1) is satisfied:
• 2.5<(Hf/Hn)/(Bf/Bn)<15.0 (1)
• where, Hf:
• a size of the primary display image in an arbitrary direction when the virtual image is displayed at a position farthest from the observer,
• Hn:
• the size of the primary display image in the arbitrary direction when the virtual image is displayed at a position closest to the observer,
• Bf:
• a display magnification of the virtual image at the position farthest from the observer, and
• Bn:
• the display magnification of the virtual image at the position closest to the observer, and
• wherein
• the size of the primary display image in the arbitrary direction indicates the size of either of a horizontal size and a vertical size of the primary display image corresponding to a horizontal direction and a vertical direction at a time of display of a virtual image, and
• the display magnification of the virtual image pertains to a ratio of the size of the primary display image in relation to the display size of the virtual image in the arbitrary direction.