A medicament delivery device and a controller is disclosed. The medicament delivery device includes a medicament container, plunger rod and a resilient member. The plunger rod is in contact with a slidable stopper within the medicament container for expelling a medicament. The resilient member is used for applying a force to the plunger rod upon a delivery of the medicament. In addition, the controller is configured to detect a completion of a delivery stroke of the plunger rod according to an inductive property of the resilient member.