The present invention relates to a liquid injection device for skin, which easily form a hole on a skin in a predetermined arrangement form in order to inject liquid for treatment in an accurate position of the skin to be treated by using a needle, such that a smooth skin treatment operation is performed by performing injection of liquid for treatment to the skin in a short time, and treatment for the skin of various forms such as a narrow or long width of a skin treatment range can be performed. Also, the liquid injection device for skin of the present invention includes a vacuum relief hole to prevent liquid from flowing backward to upper portions of a needle unit and a needle driver, and has a spring and a buffer pad provided on a shaft to reduce noise during reciprocation. The liquid injection device for skin of the present invention comprises: a needle driver (100) including a driving unit (110) embedded with a cam for reciprocating an operating shaft and an operating unit (150) having the operating shaft for sliding a needle provided in a needle body； and a needle unit (500) embedded with the needle slid by the operating shaft of needle driver for reciprocating. The driving unit (110) includes: a motor (111) embedded in an inner portion, and driving the cam (113)； and a cam (113) rotated by the motor, and reciprocating the operating shaft. A buffer pad (113-1) is provided at one end of the cam to reduce noise generated when driving the operating shaft.COPYRIGHT KIPO 2018본 발명은 니들을 이용하여 치료하고자 하는 피부의 정확한 위치에 치료용 액체를 투입할 수 있도록 상기의 피부에 일정한 배열 형태로 구멍을 용이하게 형성함으로써, 피부에 치료용 액체의 투입이 빠른 시간에 이루어져 원활한 피부 치료 작업이 이루어질 뿐만 아니라 상기 피부 치료 범위의 폭이 좁거나 길게 형성된 형태 등 다양한 형태의 피부 치료가 가능하도록 한 피부용 액체 투입장치에 진공완화홀을 구비하여 액체가 니들유닛 및 니들구동기 상부로 역류하는 것을 방지하며, 축에 스프링과 완충패드를 구비하여 왕복운동시 소음을 절감시킨 피부용 액체 투입장치에 관한 것으로, 가동축을 왕복운동시키는 캠이 내설된 구동부(110)와, 니들본체에 구비된 니들을 슬라이딩시키는 가동축이 내부에 구비된 가동부(150)로 구성된 니들구동기(100)와； 니들구동기의 가동축에 의해 슬라이딩되어 왕복운동하는 니들이 내설된 니들유닛(500)를 포함하는 피부용 액체 투입장치에 있어서,상기 구동부(110)는 내부에 내
