A device for delivery of medicament, comprising: - an elongated housing; - a container having a needle and mounted within said housing and adapted to contain a liquid medicament; - a stopper slidably arranged within said container; - actuating means comprising a resilient member, a plunger rod having a proximal end in contact with the stopper and a distal end being operably connected to the resilient member; - a carrier which is fixedly arranged to the inner surface of the housing; retaining means pivotally arranged to the carrier and comprising a protrusion arranged to be in contact with a groove of the plunger rod for releasably retaining said plunger rod in a first position where said resilient member has an accumulated energy; and - activating means operably connected to said retaining means for releasing said plunger rod to a second position, upon actively operation by an user, such that said accumulated energy is transferred to the plunger rod for driving the stopper a predetermined distance within the container whereby the medicament within said container is delivered characterized - in that said activating means comprises a tubular member mounted to said housing and at least one resilient means operably connected to said tubular member, wherein said tubular member comprises an end portion adapted to be retractable with respect to said housing against the force of said resilient means when said end portion is pushed against a delivery site such that the needle is penetrated into a delivery site, and wherein said tubular member is adapted to be urged in the direction of said end portion by the at least one resilient means when said end portion is removed from the delivery site, - in that the resilient member is a variable force spring having one end attached to the carrier and a second end, which is variably wound, cradled on the second end of the plunger rod and wherein said variable force spring is adapted for generating a predetermined sequence of at least two different force profiles during the medicament delivery, and wherein the last force profile in said sequence is a profile where the force increases as the spring relaxes, and - in that the variable force spring is a coil spring of band material and wherein the different force profiles are obtained by suitably adjusting the material and/or the geometry and/or the natural radius and/or the elastic modulus of the spring. - an elongated housing; - a container having a needle and mounted within said housing and adapted to contain a liquid medicament; - a stopper slidably arranged within said container; - actuating means comprising a resilient member, a plunger rod having a proximal end in contact with the stopper and a distal end being operably connected to the resilient member; - a carrier which is fixedly arranged to the inner surface of the housing; retaining means pivotally arranged to the carrier and comprising a protrusion arranged to be in contact with a groove of the plunger rod for releasably retaining said plunger rod in a first position where said resilient member has an accumulated energy; and - activating means operably connected to said retaining means for releasing said plunger rod to a second position, upon actively operation by an user, such that said accumulated energy is transferred to the plunger rod for driving the stopper a predetermined distance within the container whereby the medicament within said container is delivered - in that said activating means comprises a tubular member mounted to said housing and at least one resilient means operably connected to said tubular member, wherein said tubular member comprises an end portion adapted to be retractable with respect to said housing against the force of said resilient means when said end portion is pushed against a delivery site such that the needle is penetrated into a delivery site, and wherein said tubular member is adapted to be urged in the direction of said end portion by the at least one resilient means when said end portion is removed from the delivery site, - in that the resilient member is a variable force spring having one end attached to the carrier and a second end, which is variably wound, cradled on the second end of the plunger rod and wherein said variable force spring is adapted for generating a predetermined sequence of at least two different force profiles during the medicament delivery, and wherein the last force profile in said sequence is a profile where the force increases as the spring relaxes, and - in that the variable force spring is a coil spring of band material and wherein the different force profiles are obtained by suitably adjusting the material and/or the geometry and/or the natural radius and/or the elastic modulus of the spring.