To provide a motor controller which specifies a factor of abnormality occurrence in a shorter time.

A motor controller 100 includes control means of driving a motor 1 on the basis of a command signal commanding the operation of the motor 1 and a detection signal as a detection result of the operation of the motor; abnormality detection means 9 of detecting abnormality of the motor on the basis of the detection signal, the driving position and driving speed of a load machine that the motor drives, and an observation signal which is a signal generated in the control means or an external sensor signal; abnormal-time data storage means 11 of storing values of a plurality of observation signals in abnormality occurrence a plurality of times each time abnormality occurs; and dependency determination means 12 of extracting an observation signal that the abnormality occurrence depends upon based upon values of the plurality of observation signals in the abnormality occurrence which are stored in the abnormal-time data storage means.