To provide a DC motor control unit capable of facilitating control of the maximum torque generated by a DC motor without performing a complex operation.

This DC motor control unit includes: the DC motor for driving a roller; a motor driver for driving the DC motor; an encoder for outputting speed information according to rotation of the roller; and a control means for performing feedback control based on the speed information output from the encoder to output a control signal having a PWM waveform to the motor driver. The control means changes the duty value of the PWM waveform based on the speed information output from the encoder and a threshold value.