Disclosed herein are a system and a method for controlling a speed of a motor. The method for controlling a speed of a motor includes: receiving a signal from a hall sensor of the motor to measure a current speed of the motor; comparing the current speed of the motor measured with a reference speed to calculate errors; outputting a speed control value of the motor based on the calculated errors; limiting the output speed control value to values within a predetermined range; controlling a duty or a phase of current applied to the motor according to the limited values within the predetermined range; and generating a motor driving signal based on the duty control or the phase control and applying the generated motor driving signal to the motor.