An image forming apparatus characterized by comprising: an optical scanning device including a light source element (11R, 11G, 11B) configured to radiate a light beam, an optical deflector configured to deflect the light beam two-dimensionally, and a target scanning surface that is transparent and having a two-dimensional image formed thereon by the light beam deflected from the optical deflector; and a projection optical system including a convex mirror and configured to enlarge and project the two-dimensional image on a target projection surface; wherein the target projection surface includes a reflection surface of a half mirror, wherein the half mirror is configured to transmit a part of a light incident on the half mirror and reflect another part of the light incident on the half mirror, the two-dimensional image formed on the target scanning surface is visually recognizable by a user as an enlarged virtual image at a predetermined position on a side of the half mirror opposite the reflection surface of the half mirror; and characterized in that: the convex mirror is convex on a side of the convex mirror that is configured to reflect light propagating between the target scanning surface and the target projection surface through the projection optical system; and the optical scanning device further comprises a concave mirror, the two-dimensional image being formed on the target scanning surface by the light beam reflected by the concave mirror from the optical deflector. an optical scanning device including a light source element (11R, 11G, 11B) configured to radiate a light beam, an optical deflector configured to deflect the light beam two-dimensionally, and a target scanning surface that is transparent and having a two-dimensional image formed thereon by the light beam deflected from the optical deflector; and a light source element (11R, 11G, 11B) configured to radiate a light beam, an optical deflector configured to deflect the light beam two-dimensionally, and a target scanning surface that is transparent and having a two-dimensional image formed thereon by the light beam deflected from the optical deflector; and a projection optical system including a convex mirror and configured to enlarge and project the two-dimensional image on a target projection surface; wherein the target projection surface includes a reflection surface of a half mirror, wherein the half mirror is configured to transmit a part of a light incident on the half mirror and reflect another part of the light incident on the half mirror, the two-dimensional image formed on the target scanning surface is visually recognizable by a user as an enlarged virtual image at a predetermined position on a side of the half mirror opposite the reflection surface of the half mirror; and characterized in that: the convex mirror is convex on a side of the convex mirror that is configured to reflect light propagating between the target scanning surface and the target projection surface through the projection optical system; and the optical scanning device further comprises a concave mirror, the two-dimensional image being formed on the target scanning surface by the light beam reflected by the concave mirror from the optical deflector.