An encoder includes a scale having a pattern column with patterns periodically changing a physical characteristic, a detection element array disposed movable relatively to the scale and including detection elements configured to detect light from the pattern column are arranged in a moving direction, a signal processor configured to convert an output signal from the detection element array into position information. The detection element array includes first to fourth detection elements are arranged in order of the first detection elements, the second detection elements, the first detection elements, the second detection elements, the third detection elements, the fourth detection elements, the third detection elements, and the fourth detection elements. The signal processor generates a first signal based on an output signal from the first and third detection elements and a second signal based on an output signal from the second and fourth detection elements.