Disclosed is an automatic injection device comprising a housing including a main housing, a needled syringe with a plunger having fixing teeth passing through an opening in the fixed element inside the main housing, a button rotatable between a first and a second angular positions relative to the main housing and the plunger teeth. The teeth are provided with fixing surfaces and include inclined surfaces. The button includes an actuating member for interaction with inclined surfaces relative to the main housing for moving the teeth to disengage them from the fixed element so that the teeth can pass through the opening in the fixed element, and a biasing member for moving the needled syringe inside the housing when the teeth are disengaged from the fixed element to extend the syringe needle beyond the housing, the teeth passing through the opening in the fixed element, and for advancing the plunger to perform an injection. The automatic injection device includes locking projections made integral with the inclined surfaces of the teeth and extending upwards from the inclined surfaces toward the button, wherein the tips of the locking projections are positioned at a definite distance from the tips of the teeth surfaces forming therebetween radial gaps receiving the actuating member of the button when the button is in the first angular position, and the rest of the button actuating element, by means of the locking projections, prevents movement of the fixing teeth of the surfaces from the position of engagement with the fixed element； and the actuating member of the button includes deflecting slots passing inside the radial gaps when the button is in the second angular position, the locking projections can be placed into the deflecting slots so that they do not prevent movement of the fixing teeth of the surfaces from engagement with the fixed element.Описано автоматическое инъекционное устройство, содержащее корпус, включающий главный корпус, шприц с иглой и поршнем, с
