The present invention relates to an injection device for dispensing of a liquid medicament, the device comprising: a base (10), a medicament reservoir (20) displaceably arranged on the base (10) and containing the liquid medicament (25), an injection needle (30) displaceably arranged relative to the base (10) between a retracted position (30a) and an extended position (30b), a pressure container (40) containing a pressurized fluid (24), a reservoir displacing arrangement (50) coupled with the pressure container (40) to displace the medicament reservoir (20) into a dispensing position (20b), in which the medicament reservoir (20) is in fluid communication with the injection needle (30), a needle displacing arrangement (60) coupled with the pressure container (40) to at least displace the injection needle (30) into the extended position (30b).