A reflection unit reflects an image indicated on an indicator and projects the image on a combiner to indicate a virtual image of the image at a position viewable for a user. A stepping motor rotates the reflection unit to move the virtual image continuously in a predetermined section of the combiner. A control unit controls a driving power of the stepping motor such that a smoothness parameter becomes less than a predetermined value. The smoothness parameter is defined by a division of a difference between the maximum speed of the virtual image and an average speed of the virtual image, when the virtual image moves continuously in the predetermined section, by the average speed.