The present invention relates to a pen-type portable insulin infusion device, and more particularly is selected automatically according to a users / relates to a portable insulin injection pen injection device having a manual switchover function. Pen-type portable insulin injection device according to the present invention, comprises a drive unit with a piston and a pushing unit auto / manual switching means. Pushing piston unit is a through hole formed in the longitudinal direction and the pusher housing and rotatably connected to the case, and the gear box from the one end to receive a rotating force transmission gear box is connected to the through hole of the pusher housing and inserted around the shaft , accept a pusher installed in the through hole of the housing and deliver the rotational force of the transmission shaft includes a pusher that is constrained to slide within the through hole of the pusher housing in the longitudinal direction. Auto / manual switching means and release the restraint of the case and the pusher housing to prevent relative rotational movement is restrained, and the rotational force around the plurality of gears of the gear box to be delivered to any one of the gears of the motor shaft at the same time in the first position, The constraining the case with Fuchsia housing relative rotation to release the restraint and the movement of the plurality of gears to prevent rotation of any of the gear of the gearbox is not passed at the same time in all the rotational force of the motor shaft in the second position.본 발명은 펜형 휴대용 인슐린 주입 장치에 관한 것으로서, 보다 상세하게는 사용자의 선택에 따라서 자동/수동 전환 주입 기능을 갖는 펜형 휴대용 인슐린 주입 장치에 관한 것이다.본 발명에 따른 펜형 휴대용 인슐린 주입 장치는, 구동유닛과, 피스톤 푸싱유닛과 자동/수동 전환수단을 포함한다. 피스톤푸싱유닛은 길이방향으로 관통구멍이 형성되어 있고 케이스에 회전가능하게 연결된 푸셔하우징과, 상기 기어박스로 부터 회전력을 전달받도록 일단이 기어박스에 연결되고 푸셔하우징의 관통구멍에 삽입된 전동축과, 푸셔하우징의 관통구멍 내부에 설치되고 전동축의 회전력을 전달받아 푸셔하우징의 관통구멍 내부에서 길이방향으로 슬라이딩하도록 구속된 푸셔를 포함한다. 자동/수동 전환수단은 제1위치에서 케이스와 푸셔하우징이 상대 회전 운동을 하지 못하도록 구속하고 동시에 모터의 회전력이 전동축에
