A medicament delivery device includes a housing arranged to accommodate a medicament container, and a drive unit operably arranged to act on an accommodated medicament container for expelling a dose of medicament. The drive unit includes a plunger rod, a force element operably connected to the plunger rod, a connector arranged to releasably hold the plunger rod, an actuator element operably arranged to the connector, and a manually operable actuator arranged to act on the actuator element for releasing the connector when operated. A safety device is arranged to releasably hold the actuator element in a locking position with the connector, preventing unintended release of the plunger rod.