Provided is an encoder that can sense an abnormality in the attitude of a detector with respect to a scale. An encoder includes a scale and a detector, the scale being provided on one measurement target part with marks arranged on the scale, and the detector being provided on another measurement target part and configured to detect an amount of relative movement with the scale. The scale includes a sensing unit that senses the attitude of the detector with respect to the scale, and thus even in a case where an abnormality in the attitude of the detector with respect to the scale cannot be sensed on the basis of a change in a signal read by a reading unit, the abnormality can nevertheless be sensed.