A noise reduction pinion gear structure is disclosed, wherein the noise reduction pinion gear structure comprises a pinion portion of a metal material and a contact gear portion of a synthetic resin material coupled to the pinion portion Wherein the pinion portion includes a power receiving portion formed around a front end of the pinion portion to receive external power and a nulling portion formed around the rear end of the pinion portion to increase frictional resistance between the pinion portion and the contact gear portion, A fastening force increasing groove for increasing a fastening force of the pinion portion and the contact gear portion because a corresponding portion of the contact gear portion is inserted when a plurality of elastically deformed contact gear portions are formed around the rear end of the pinion portion, And a shear step formed The contact gear portion includes a gear formed on an outer circumferential surface and adapted to transmit a rotational power transmitted from the pinion portion to the outside, an engaging hole formed to penetrate the center portion and penetratingly fitting the knurled portion of the pinion portion, And a knurling protrusion formed on the front end of the engaging hole to prevent the burring of the pinion portion from being discharged to the outside of the engaging hole when the knurled portion of the pinion portion is interference fit with the engaging hole, And a burr receiving space formed by the space between the stepped end of the pinion part and the burr supporting jaw of the contact gear part when fully engaged with the engaging hole so that the burr is accommodated.소음 경감 피니언 기어 구조체가 개시되며, 상기 소음 경감 피니언 기어 구조체는, 금속재의 피니언부와, 상기 피니언부에 결합되는 합성수지재의 밀착기어부로 이루어지고 상기 피니언부는, 상기 피니언부의 전단 둘레에 형성되어서 외부의 동력이 전달되는 동력수용부와, 상기 피니언부의 후단 둘레에 형성되어서 상기 밀착기어부와의 마찰저항을 증대시키는 널링부와, 널링부 사이의 상기 피니언부 후단 둘레에 복수개 형성되어서 탄성 변형된 밀착기어부가 복원될시 상기 밀착기어부의 대응 부분이 삽입되므로 상기 피니언부 및 상기 밀착기어부의 체결력을 증대시키는 체결력증대홈과, 상기 피니언부의 후단 둘레에 형성되는 전단단턱으로 이루어지며
