PURPOSE: To provide a motor controller in which design time for control system can be shortened by performing an optimal feedforward control without requiring calculation of gain.

CONSTITUTION: The motor controller comprises a current minor loop 9, a speed minor loop 7, a switch 1 for switching a controller between a test mode and an actual motion mode, and a test current generating section 2 for commanding various test currents to the current minor loop 9 under test mode. The motor controller further comprises an actual acceleration detecting section 3 for detecting the actual acceleration of motor due to the test current, a target acceleration operating section 5 for operating a required target acceleration from a commanded target speed, and a table section 4 in a feedforward control section for preparing a correspondence table of test currents and actual motor accelerations and calculating a current value required for obtaining a target acceleration from the correspondence table to command the current minor loop 9.