An injector device, and a method for its operation. For containers with an opening for an injection needle e.g. a syringe. The injector comprises a housing, a seat or a carrier arranged to hold the needle and for allowing movement thereof in relation to the housing between a rear, needle-covering, position and a forward, needle exposing position. It further comprises a penetration arrangement operable to move the needle from the rear position to the forward position, a return arrangement to move the needle in the rearward direction, and an injection arrangement to expel container content through the needle. It also comprises a control button arranged on the housing, which, through a transmission and a switch system, stepwise trigs the penetration arrangement and injection arrangement. The button is arranged to have a least a movement component perpendicular to the needle axis.