A motor and a rotary assembly of the motor are provided. The motor includes a rotary assembly and a stationary assembly supporting the rotary assembly. The rotary assembly includes a rotary shaft, a retainer rotating along with the rotary shaft, and a rotor magnet retained by the retainer. A portion of the rotor magnet engages with a portion of the retainer via interference fit, and a gap is defined between another portion of the rotor magnet and another portion of the retainer.