A method of calibration includes determining whether thermal expansion has been detected the electric mechanical brakes when a braking force is generated; performing a first calibration to calibrate each electric mechanical brake in which thermal expansion has been detected while the vehicle is running; performing a second calibration to calibrate each electric mechanical brake that has been calibrated in the first calibration after the vehicle is stopped; and determining whether thermal expansion has been detected in the electric mechanical brakes and calibrating the air gaps of the electric mechanical brakes in a preset order after the vehicle is stopped, when it is not determined that thermal expansion has been detected in any one of the electric mechanical brakes while a braking force is being generated in the running vehicle.
