Mirror device and vehicle display device

A vehicle display device comprising:

• a casing that has an opening;
• an image display device that is provided in the casing and outputs display light for an image;
• and
• a mirror device that is provided in the casing, wherein
• the mirror device includes
• a mirror that includes a main body having a reflective surface that reflects the display light from the image display device toward the opening, and a rotation shaft protruding from a side wall of the main body,
• a motor that includes an output shaft disposed on a rotation axis of the rotation shaft, and
• a power transmission member that transmits a driving force of the motor to the rotation shaft, and
• first assembling portions to be fitted to each other in a direction along the rotation axis at positions adjacent to the rotation shaft are formed at the power transmission member and the mirror.