The encoder includes a plurality of slit tracks, a point light source, two first light-receiving arrays, two second light-receiving arrays, and a third light-receiving array. The plurality of slit tracks respectively comprises a plurality of reflection slits arranged along a measurement direction. The point light source is configured to emit diffusion light to the plurality of slit tracks. The two first light-receiving arrays are disposed sandwiching the point light source in a width direction substantially orthogonal to the measurement direction. The two second light-receiving arrays are disposed sandwiching the point light source in the measurement direction. The third light-receiving array is configured to receive light reflected by the slit track comprising an incremental pattern that differs in pitch from other incremental patterns, and is disposed at a position in a direction where the first light-receiving array is disposed than the point light source.