The invention provides a barrel with an attached cap a prefilled syringe and a cap with an attached connector that can handle both Luer Lok type connection fittings and slip in type connection fittings. In the invention a connector (3) which is separably connected to a cap (2) and separates from a barrel (1) together with the cap (2) when mounted on the barrel (1) via the cap (2) at an initial position is characterized in being equipped with a connector engaging part (33) that engages with a barrel engaging part (13) of the barrel (1) at a mounting position that is closer to the base end than the initial position in the axial direction of the barrel (1) so that the connector separates from the cap (2) and is mounted on the barrel (1) when the cap separates from the nozzle part (11).
