An encoder includes a plurality of slit tracks, a point light source, a first to third light-receiving arrays. The plurality of slit tracks respectively comprises a plurality of reflection slits. The point light source emits diffusion light to the plurality of slit tracks. The first light-receiving array receives light reflected by the slit track comprising an incremental pattern. The second light-receiving array receives light reflected by the slit track comprising an incremental pattern longer in pitch than other incremental patterns, and is disposed at a position on a side of a direction where the point light source is disposed, than the first light-receiving array, The third light-receiving array receives light reflected by the slit track comprising an absolute pattern, and is disposed at a position on a side of a direction where the point light source is disposed, than the first light-receiving array.