A washing apparatus comprising: a tub provided in a cabinet ; a drum rotatably provided in the tub; a balancer housing installed in a front or rear portion of the drum, the balancer housing including a first inner circumferential surface and a second inner circumferential surface facing the first inner circumferential surface; and a balancing unit comprising a driving motor and a driving gear for being provided with power from the driving motor, the balancing unit being configured to be movable within a space formed between the first inner circumferential surface and the second inner circumferential surface , so as to reduce eccentricity of the drum, and gear teeth arranged along the first inner circumferential surface of the balancer housing , wherein the balancer housing includes a balancer housing base and a balancer housing cover , the balancer housing cover is capable of being decoupled from the balancer housing base , and the balancing unit is installed in the balancer housing base so that the driving gear exposed outside a body of the balancing unit engages with the gear teeth , and characterized in that the gear teeth include one or more inclined portions formed in a width direction thereof at a side facing toward the balancer housing cover , and the one and more inclined portions include a first inclined portion defined by two inclined surfaces, and said two inclined surfaces are spaced apart in both sides of the central line (C3) crossing the gear teeth in a height direction (h) of the gear teeth and converged to a central line (C2) running along the width direction of the gear teeth as getting closer to a width-direction end of the gear teeth at a side facing toward the balancer housing cover , and guide the driving gear upon installing the balancing unit into the balancer housing cover . a tub provided in a cabinet ; a drum rotatably provided in the tub; a balancer housing installed in a front or rear portion of the drum, the balancer housing including a first inner circumferential surface and a second inner circumferential surface facing the first inner circumferential surface; and a balancing unit comprising a driving motor and a driving gear for being provided with power from the driving motor, the balancing unit being configured to be movable within a space formed between the first inner circumferential surface and the second inner circumferential surface , so as to reduce eccentricity of the drum, and gear teeth arranged along the first inner circumferential surface of the balancer housing , wherein the balancer housing includes a balancer housing base and a balancer housing cover , the balancer housing cover is capable of being decoupled from the balancer housing base , and the balancing unit is installed in the balancer housing base so that the driving gear exposed outside a body of the balancing unit engages with the gear teeth , and characterized in that the gear teeth include one or more inclined portions formed in a width direction thereof at a side facing toward the balancer housing cover , and the one and more inclined portions include a first inclined portion defined by two inclined surfaces, and said two inclined surfaces are spaced apart in both sides of the central line (C3) crossing the gear teeth in a height direction (h) of the gear teeth and converged to a central line (C2) running along the width direction of the gear teeth as getting closer to a width-direction end of the gear teeth at a side facing toward the balancer housing cover , and guide the driving gear upon installing the balancing unit into the balancer housing cover . <EOS>