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 (932, 934) formed in a width direction thereof at a side facing toward the balancer housing cover, and the one and more inclined portions (932, 934) 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 crossing the gear teeth in a height direction (h) of the gear teeth and converged to a central line 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 (932, 934) formed in a width direction thereof at a side facing toward the balancer housing cover, and the one and more inclined portions (932, 934) 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 crossing the gear teeth in a height direction (h) of the gear teeth and converged to a central line 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.