A mobility assistance device and a driving method thereof are provided. The mobility assistance device includes at least one bracket and a driving device which drives the at least one bracket. The driving device includes a brushless direct current (DC) motor, a rotor angle sensor, and a sensing driver. The rotor angle sensor senses the angle of the brushless DC motor. The sensing driver uses a corresponding algorithm to estimate a corresponding angle corresponding to an angle velocity switching of the brushless DC motor. The corresponding angle is used as an angle of the brushless DC motor. The sensing driver drives the brushless DC motor according to the corresponding angle, so that the brushless DC motor provides supporting force to the at least one bracket.