The present invention provides a method for calibrating an encoder which includes a scale and a light receiving unit configured to receive light reflected by the scale, and detects a change in relative position between the scale and the light receiving unit, the method comprising a measurement step of measuring a deformation amount of a surface shape of the scale, a specifying step of specifying, based on a measurement result in the measurement step, a range which includes a portion of a surface of the scale, where the deformation amount exceeds a threshold, and within which a detection value of the encoder is corrected, and a determination step of determining a correction value for correcting the detection value of the encoder within the range specified in the specifying step.