The optical encoder includes a scale provided with a scale pattern reflecting or transmitting light from a light source, and a sensor receiving the light from the scale pattern. The sensor is provided with a light-receiving element array. The light-receiving element array includes multiple light-receiving element groups with a pitch P. Each group is constituted by two or more light-receiving elements whose outputs are added together. An intermediate pattern is provided between the scale and the sensor. The intermediate pattern includes a first pattern to form a first light intensity distribution with a first spatial period shorter than the pitch P on the light-receiving element array and a second pattern to form a second light intensity distribution with a second spatial period longer than the pitch P on the light-receiving element array.