Disclosed is an apparatus for changing a mode in a proportional integral differential (PID) controller, which removes an impact generated in a mode change and stably performs the mode change when the operational mode of the PID controller is changed from a manual mode into an automatic mode or vice versa. The apparatus includes a PID operator configured to generate a driving signal by performing a PID operation in an automatic mode or a manual mode based on a manual mode change signal or an automatic mode change signal; a manual mode buffer configured to process the generated driving signal and output the processed driving signal to a load driver when the manual mode change signal is generated; and a speed difference integral calculator configured to analyze the generated driving signal and output the analyzed driving signal to the PID operator when the automatic mode change signal is generated.