In a device (1) for automatically injecting injection liquids, including an axially subdivided housing whose parts are connectable with each other, wherein an axially displaceable pressure pin (5) is guided in a first housing part (2), which pin is capable of being inserted against a force accumulator (6) and locked in the inserted position and extended upon relief of the force accumulator (6), wherein an injection needle (15) fixed in a needle guide (14) and an ampoule (13) are mounted in a second housing part (3) so as to be axially displaceable relative to each other, wherein the injection needle (15) on its side facing the ampoule (13) is designed as a perforation piece (32) for the ampoule (13), the ampoule (13) with its end facing the injection needle (15) is mounted to reach into a sleeve (16) fixed within the second housing part (3) and whose inner diameter substantially corresponds to the outer diameter of the ampoule (13). Radially inwardly protruding projections (17) are formed on the inner periphery of the sleeve (16), and the sleeve (16) comprises locking members cooperating with locking members (20) of the needle guide (14), whereby an axial displacement of the ampoule (13) in the direction to the needle guide (14) while overcoming the displacement resistance exerted by the projections (17) causes the release of the locking members (20) and the axial displaceability of the needle guide (14).
