An optical combining device for combining the paths of two light beams having different polarizations is provided. The device includes a scroll direction change prism and a polarized beam splitter. The scroll direction change prism is disposed in the path of a first light beam and changes a scroll direction of the first light beam to as to be the same as that of a second light beam. The polarized beam splitter is disposed in the path of both the first light beam, reflected from the scroll direction change prism, and the second light beam and combines the first and second beams by selectively transmitting or reflecting them according to the polarization direction thereof.