The present invention provides a projection apparatus, comprising: a light source; a plurality of spatial light modulators each comprising a micromirror for modulating and deflecting an incident light emitted from the light source in an intermediate direction between a first and a second directions and all angles between the first and second directions The projection apparatus further includes a projection optical system for projecting a modulation light modulated by the spatial light modulator The projection apparatus further includes a first joinder prism comprising a first optical surface with at least two of the incident lights with different frequencies projected thereto, a second optical surface for ejecting the incident light incident from the first optical surface and for projecting the modulation light thereto, and a selective reflection surface for reflecting the incident light incident from the first optical surface and transmitting the modulation light. The projection apparatus further includes and a second joinder prism comprising a third optical surface with the modulation light ejected from the first joinder prism transmitted thereto, a synthesis surface for synthesizing the modulation lights with different frequencies incident from the third optical surface transmitted in the same light path, and an ejection surface disposed at a position approximately opposite to the projection optical system for ejecting a synthesized light synthesized on the synthesis surface, wherein the first optical surface is approximately perpendicular to the synthesis surface.