To obtain connected containers to improve accuracy of the bacteria test, workability and safety by connecting a blood bag to store sampled blood, a culturing container of bacteria to culture bacteria, etc., with specified tubes.

These connected containers 1 consist of a blood bag 10, a blood plasma bag 20, a buffy coat bag 30, a blood platelet bag 40 and a culturing container 50 to culture bacteria with specified tubes. A branching connector 92 is connected to the halfway of a tube 15 which has the one end connected to the blood bag 10 and to the other end a sampling needle 152 is attached. The one end of a tube 91 is connected to the branching connector 92 while the other end is connected to the bacteria culturing container 50. A sealing member 93 and a check valve 94 are attached to the halfway of the tube 91. It is preferable to introduce a culture medium into the culturing container 50 before a part of blood is introduced to the culturing container 50 and then to culture bacteria.