A reflection type optical sensor that detect a surface condition of a moving body and that is used for an image generation apparatus which forms images on a recording media includes a light-emitting device which has a plurality of light emitter systems including at least two light-emitting members and a light-emitting optical system having a plurality of light-emitting lenses corresponding to a plurality of the light emitter systems and guiding light emitted from the light emitter systems to the moving body and a light-receiving device which has a light receiver system including at least two light-receiving members and a light-receiving optical system having light-receiving lenses corresponding to the at least two light-receiving members and guiding light reflected by the moving body to the light receiver system. The image generation apparatus has further a surface condition judging device in addition to the reflection type optical sensor.