Head-up display device

A head-up display device comprising:

• an image display device configured to output display light of an image;
• a rotatable mirror having a reflecting surface configured to reflect the display light toward a reflecting portion arranged in front of a driver, and an input shaft;
• a motor having an output shaft located on an extended line of the input shaft, the motor being configured to rotate the output shaft;
• a transmission member having a cylindrical fitting portion to which the input shaft is press-fitted and a coupling portion coupled with the output shaft, the transmission member being configured to transmit output torque of the motor from the output shaft to the input shaft;
• a holding member holding the motor;
• and
• a first spring interposed between the holding member and the transmission member, the first spring being configured to impart, to the transmission member, a biasing force oriented to bring the mirror close to the output shaft along an axial direction of the input shaft,
• wherein the cylindrical fitting portion and the coupling portion of the transmission member are integral and rotate in the same direction.