An image forming medium changing device includes a changing unit configured to change a characteristic of an image forming medium on which projected light is focused, wherein the projected light is refocused on an aerial space image forming section by a light guide optical system. A spatial projection apparatus including the image forming medium changing device includes multiple image forming media having different characteristics, and the changing unit is configured to be driven to dispose one image forming medium selected from the multiple image forming media on an image forming effective area interposed between a light source of the projected light and the light guide optical system.