Abstract: The present invention relates to a portable mechanical insulin injection device comprising i) a mechanical insulin injection device (10) wherein said injection device is mechanically operated by hand-operated rotating part (106) whereas the amount of injected insulin and the pre-determined injection amount of insulin are electrically controlled and displayed by electrical control panel (110); and E) an insulin injection unit (20) wherein an insulin injection needle (211) is inserted in the skin or muscle of patient and an insulin injection connector (215) is fixed with the insulin outlet of mechanical insulin injection device (10) at the time of insulin injection.