FIELD: medicine.SUBSTANCE: invention relates to medical equipment, and deals with a drive mechanism, intended for a device for a medicinal substance delivery, which makes it possible for the user to select a single dose or a multitude of doses of the injected medication, give out specified doses of the medication and introduce the said medication to a patient, preferably by injection. The drive mechanism of the device for the delivery of the medicinal substance, intended for giving out the medication dose, contains a holder for a cartridge, containing the medication a piston rod, made with a possibility of an engagement with the cartridge piston for giving out the medication dose at least one regulating unit and blocking means. The cartridge has a piston, located in it with a possibility of displacement in the axial direction. At least one regulation unit is located with a possibility of sliding in the axial direction relative to the piston and/or relative to the piston rod to eliminate an axial clearance between the piston and the piston rod. The regulation unit is fixed to the proximal butt end of the piston or is preliminarily assembled with the distal part of the piston rod and additionally contains a socket for the reception of the distal part of the piston rod. The blocking means is made with a possibility of interaction with the regulation unit for blocking in its place the distal part of the piston rod in the arbitrary position inside the regulation unit socket to create mechanical connection, which is rigid when working on compression, the piston rod and the piston, independent on a relative distance between the piston and the piston rod. The device for the medicinal substance delivery, intended for giving out the medication dose, contains a case and a cartridge, containing the medication. The cartridge additionally contains a piston, placed with a possibility of sliding in the axial direction. The device additionally contains the said drive mechanism. The
