Abstract: An injector serving for injection of an injection fluid is described. The injector includes a housing with a contact face for during injection supporting on the skin of a person. The injection fluid is placed in a chamber in the housing which furthermore contains an injection needle placed, in a direction of activation intersecting both the at least one chamber and the contact face, displaceably in the housing from a position of rest where the needle point is in front of the at least one chamber—seen in the direction of activation—to an injection position where the point has penetrated the skin. In the point is furthermore made an eye for, at activation of the injector, receiving a fixed quantity of injection fluid during the passage of the chamber, and after this, there is placed a membrane with a slot which during the injection process fits tightly around the needle and thereby sweeps off all fluid except for the fluid in the eye.