An administration assembly for a medicament delivery device is presented having a plunger rod, a plunger rod holder and an activation sleeve configured to receive a portion of the plunger rod holder. The triggering member is configured to move the activation sleeve from a first position to a second position relative to the plunger rod holder. The plunger rod is configured to be axially locked relative to the plunger rod holder when the activation sleeve is in the first position. The plunger rod is released from being axially locked when the activation sleeve is moved towards the second position.
