A medicament delivery device (1) comprises a housing (2) for holding a medicament cartridge (9), a drive (18, 32) and a drive control means (46, 52). The medicament cartridge (9) has a medicament outlet and a bung (20) able to be driven via a piston rod (12, 14) driven by the drive force of the drive (18, 32) and controlled by the drive control means (46, 52). Additionally, the medicament delivery device (1) comprises a restraining means (38) for applying a restraining force to the piston rod (12, 14), in a direction opposite to the drive force. By varying the restraining force by the drive control means (46, 52) the movement of the bung (20) along the medicament cartridge can be controlled.
