The present invention relates to a continuous injector for an animal, comprising an external casing, an injection solution storage case, a piston stand, an injector case, and an elastic spring. The external casing has a cylindrical case of which the front and the rear are opened. A front coupler and a rear coupler are mounted on the front and the rear of the external casing. The injection solution storage case is inserted into the external casing, and stores an injection solution therein. The piston stand includes a pipe type piston housing, a piston body, and a first injection solution control cap. The piston housing is inserted into the front of the inside of the external casing, so that the front of the piston housing passes through the front coupler to protrude outward. The piston body is provided inside the piston housing. The piston body has an injection solution supply passage punched in the center thereof. The injection solution storage case is connected to the rear of the injection solution supply passage. The first injection solution control cap for controlling the opening or closing of the injection solution supply passage is mounted on the front end of the piston body. The injector case is a cylindrical pipe of which the rear is opened. The injector case is filled with the injection solution supplied through the injection solution supply passage from the injection solution storage case. The injector case is inserted into a space part between the piston housing and the piston body while the injector case is inserted into and coupled with the external circumference of the piston body, so that the injector case is installed to be movable frontward and rearward. A control cap mounting element, on which a second injection solution control cap for controlling the discharge of the injection solution is mounted, is inserted into and coupled with the front of the injector case. A front stopper into which an injector needle is inserted is coupled with the front of
