To stop a control target driven by a motor for printers at a target position accurately as much as possible.

The control device of a motor with a speed control for performing acceleration, constant-speed, and deceleration control of a control target driven by a motor by controlling current applied to a motor 4 for printers is provided with an inertia operation part 93 for calculating inertia to be controlled, based on the angular velocity of the motor in the case of the acceleration control of a control target 3 and a current applied to the motor in the case of the acceleration and constant-speed control of the control target. The speed control controls current to the motor using the calculated inertia.