The present invention provides an optical scanning device, an imaging display device and a retinal scanning display which can be further miniaturized. The optical scanning device includes a vertical scanning system for scanning an incident optical flux in a primary direction and a horizontal scanning system for scanning the optical flux scanned in a secondary direction intersecting the primary direction. The optical scanning device further includes a relay optical system arranged between a Galvano mirror in the vertical scanning system and a Galvano mirror in the horizontal scanning system. The relay optical system includes at least a condensing mirror for guiding the optical flux scanned in the primary direction by the Galvano mirror in the vertical scanning system to the Galvano mirror in the horizontal scanning system.