In an infusion set, a spike or a connector for connection with an intravenous drip needle is covered by a cap, arranged at which there is an opening configured so as to not allow passage therethrough of solid or liquid but so as to allow passage therethrough of gas at the interior of the cap, a hydrophobic filter being arranged at a location inward from where the tip of the spike or the connector for connection with an intravenous drip needle is inserted at the interior of the cap by way of an insertion port, and a lid at the exterior of said opening for closing said opening. A three-way stopcock having a primary tubing downstream branch connector equipped with a mechanism that connects in such fashion as to permit rotation about primary tubing as axis is provided.
