PROBLEM TO BE SOLVED: To provide a mixed injection member for sufficiently sterilizing the internal space of an adaptor member and also suppressing occurrence of contamination by various bacteria when it is opened or even after the opening from a package material.SOLUTION: The mixed injection member 50 includes: a joint member the adaptor member 100 having a first connection part and a second connection part 140 and a cap member 60 configured to be attachable/detachable to/from the second connection part 140. A facing part 132 is arranged between the first and second connection parts. The adaptor member 100 and the cap member 60 are separated at a distance L3 so that the opening end surface 65 of the cap member 60 is not brought into direct-contact with the facing part 132 when the cap member 60 is mounted on the second connection part 140. When a length from the facing part 132 to the end surface 144 of the second connection part is defined as L1 and a length from the opening end surface 65 of the cap member 60 to a top surface 66 is defined as L2, a relational expression "L1
