To provide a DC motor drive unit where the drive unit is miniaturized and is made less expensive by suppressing the excessive regeneration current of a motor being generated owing to short circuit damping and reducing the rated current of a switching element to be used.

A DC motor drive unit comprises a switching element 2 for driving a brushless DC motor 3 and a speed control circuit 1 for generating a conduction signal (e) of the switching element 2 by receiving a rotary speed command signal (a) from an upper controller 1A, a start/stop signal (b), a rotary direction signal (c), a damping signal (d), and a rotary speed signal (g) of the DC motor 3. When the rotary speed signal (g) of the DC motor 3 is larger than a reference signal (j), an inversion damping signal (f) for inverting and damping the DC motor 3 is outputted. Further, when the rotary speed signal (g) of the DC motor 3 becomes smaller than the reference signal (j), all coil windings of the DC motor 3 are short-circuited and damped for switching to a short-circuiting damping signal (k) automatically by a damping control circuit 11.