HEAD-UP DISPLAY DEVICE

A head-up display device (10) includes an image display device (11) that outputs display light (DL) of an image; a mirror (2) having a reflecting surface (20a) that reflects the display light (DL) toward a reflecting portion, and an input shaft (21); a motor (4) that has an output shaft (41) located on an extended line of the input shaft (21), and rotates the output shaft (41); a transmission member (5) that has a cylindrical fitting portion (51) to which the input shaft is press-fitted and a coupling portion (52) coupled with the output shaft (41) and transmitting output torque of the motor (4) from the output shaft (41) to the input shaft (21); a holding member (3) that holds the motor (4); and a first spring (7) that is interposed between the holding member (3) and the transmission member (5), and imparts, to the transmission member (5), a biasing force (F1) oriented to bring the mirror (2) close to the output shaft (41).