A medicament delivery device comprising: a housing having a proximal end and an opposite distal end; drive means (90, 91) configured to act on a medicament container for expelling a medicament, wherein the drive means comprises a plunger rod and a resilient member which is pre-tensioned arranged within the plunger rod for exerting force to the plunger rod in the proximal direction; holding means (100, 22) configured to hold said drive means (90, 91) in a pre-tensioned state; and activation means configured to interact with said holding means for releasing the drive means from the pre-tensioned state, wherein the activation means is a tubular activation member slidably and coaxially arranged in relation to the tubular housing; wherein the holding means are a tubular extension part and a tubular operation member, wherein the tubular operation member includes a co-acting means (101, 102) interactively connected to a corresponding co-acting means of the tubular activation member, wherein the plunger rod comprises a releasable engaging means interactively connected to a corresponding co-acting means of the tubular extension part, whereby the drive means is in a pre-tensioned state when the releasable engaging means is engaged with the corresponding co-acting means, and wherein the medicament delivery device further comprising feedback means configured to interact both with said holding means and with said drive means for generating an audible and/or tactile and/or visual signal indicating that the medicament delivery has been completed, characterized in that said feedback means is a longitudinally extending signal generating member interactively connected to said tubular extension part and to said drive means, such that when the plunger rod is completely released from the tubular extension part and the longitudinally extending signal generating member, the longitudinally extending signal generating member is released from said tubular extension part and displaced distally by a remaining force of the resilient member for generating an audible and/or tactile and/or visual signal indicating that the medicament has been completely expelled. a housing having a proximal end and an opposite distal end; drive means (90, 91) configured to act on a medicament container for expelling a medicament, wherein the drive means comprises a plunger rod and a resilient member which is pre-tensioned arranged within the plunger rod for exerting force to the plunger rod in the proximal direction; holding means (100, 22) configured to hold said drive means (90, 91) in a pre-tensioned state; and activation means configured to interact with said holding means for releasing the drive means from the pre-tensioned state, wherein the activation means is a tubular activation member slidably and coaxially arranged in relation to the tubular housing; wherein the holding means are a tubular extension part and a tubular operation member, wherein the tubular operation member includes a co-acting means (101, 102) interactively connected to a corresponding co-acting means of the tubular activation member, wherein the plunger rod comprises a releasable engaging means interactively connected to a corresponding co-acting means of the tubular extension part, whereby the drive means is in a pre-tensioned state when the releasable engaging means is engaged with the corresponding co-acting means, and wherein the medicament delivery device further comprising feedback means configured to interact both with said holding means and with said drive means for generating an audible and/or tactile and/or visual signal indicating that the medicament delivery has been completed, characterized in that said feedback means is a longitudinally extending signal generating member interactively connected to said tubular extension part and to said drive means, such that when the plunger rod is completely released from the tubular extension part and the longitudinally extending signal generating member, the longitudinally extending signal generating member is released from said tubular extension part and displaced distally by a remaining force of the resilient member for generating an audible and/or tactile and/or visual signal indicating that the medicament has been completely expelled.