A needle insertor for a medicament delivery device is presented having a driver having a first part movably arranged within the case and a second part connected to the base, a needle assembly movably held by the first part in the case, a rotator arranged in the case and configured to engage the first part for moving the driver, an energy accumulation member configured to interact with the rotator for applying a rotational force on the rotator, a movable stop arranged on the base and configured to interact with the rotator for preventing the rotator from rotating. The first part has a first position where the needle assembly is held inside the case, a second position where the needle portion is positioned outside the case after being moved to pass through the injection site end, and a third position where the needle portion is positioned inside the case.