A manual injector for skin more easily percutaneously injects into the body liquid nutritional components having skin moisturization, anti-inflammation, skin irritation alleviation, whitening, and anti-wrinkle effects; and a therapeutic agent or an immune activation agent, such as a vaccine, or a skin elasticity nutritional component for skin care. The injector includes: a housing in which liquid nutritional components are charged; a coupling casing mounted to the housing; an opening and closing valve coupled to an inlet hole by passing therethrough and configured to be moveable upward and downward; a bottom casing; a pumping unit having a pressing bar provided therein; a top casing in which a needle hole is formed; and a needle.