Provided are a light source apparatus capable of preventing a shift in an optical path of a light beam, and an optical scanner comprising the light source apparatus. An optical scanner comprises a light source apparatus in which four light sources corresponding to four colors Y, M, C and B are supported as a unit by one holder. The light sources are integrally disposed in a specific position (a position where the holder is disposed) on an optical base as a supporting base, so even if distortion of the optical base occurs resulting from a dynamic load, ambient temperature or the like, an influence of the distortion is exerted upon each of the light sources supported by the holder to substantially the same extent. Even if a shift in the whole arrangement of the light sources occurs, a large shift in a positional relationship between each light source does not occur. Therefore, compared to the case where the light sources are separately arranged, a shift in a relative positional relationship between optical paths of laser beams can become less likely to occur.