A charge pump for a drug injector using an elastic force and an osmotic pressure of the present invention comprises a first chamber for storing a solvent or a solution, a first cylinder for supplying a solvent or a solution from the first chamber to the first chamber of the drug injector, A first charging unit including a first driving unit A second chamber in which a solution having a concentration higher than the concentration of the solution stored in the first chamber is stored, a solvent injected into the first chamber through the second chamber, A second charging unit including a second cylinder and a second driving unit for charging the second storage unit A third charging unit including a third chamber in which the drug is stored, a third cylinder for supplying the drug from the third chamber to the third storage unit of the drug injector, and a third driving unit A controller for controlling the first charging unit, the second charging unit, and the third charging unit based on a charged amount of a drug to be charged into a third storage unit of the drug injector and an injection amount of a drug to be injected into the human body through the drug injector [0015] FIG.Therefore, according to the present invention, the amount of the drug and the solvent are equally charged in the drug injector through the first control unit and the second control unit, the concentration of the solution filled in the drug injector and the internal pressure of the drug injector are controlled through the third control unit The injection amount of the drug injected into the human body through the drug injector can be kept constant.본 발명의 탄성력 및 삼투압을 이용한 약물주입기용 충전펌프는, 용매 또는 용액이 저장되는 제1챔버, 상기 제1챔버로부터 용매 또는 용액을 공급받아 약물주입기의 제1저장부로 충전시키기 위한 제1실린더 및 제1구동부를 포함하는 제1충전 유닛 상기 제1챔버 내에 저장된 용액의 농도보다 높은 고농도의 용액이 저장되는 제2챔버, 상기 제2챔버로부터 용액을 공급받아 상기 제1저장부 내에 충전되는 용매가 삼투현상에 의해 이동되는 상기 약물주입기의 제2저장부로 충전시키기 위한 제2실린더 및 제2구동부를 포함하는 제2충전 유닛 약물이 저장되는 제3챔버, 상기 제3챔버로부터 약물을 공급받아 상기 약물주입기의 제3저장부로 충전시키기 위한 제3실
