A rotor of a BLDC motor includes: a rotor divided into a north pole and a south pole on the basis of a magnetic pole separating line; and a stator at which the rotor is disposed with an air gap, the stator having a first pole shoe, a second pole shoe and a pair of detent grooves at its inner surface, wherein an air gap forming portion for enlarging an air gap between the rotor and the detent grooves is formed at both end portions of the rotor where the magnetic pole separating line passes, so that the rotor can maintain the motor performance and reduce resonance noise by reducing only higher degree of cogging torque from cogging torque generated when the motor is driven.