PROBLEM TO BE SOLVED: To provide a mixed injection member capable of smoothly performing collection of a fluid in an internal flow passage and injection of a fluid to the internal flow passage, and reliably preventing stagnation of a fluid in the internal flow passage.SOLUTION: A mixed injection member 1 comprises: a main body part 2 that can be connected to a blood circuit in which blood circulates； an internal flow passage &alpha； formed in the main body part 2, in which a fluid in the blood circuit can circulate； an introduction flow passage A for introducing the blood into the internal flow passage &alpha； and an introduction flow passage B for leading out the blood in the internal flow passage &alpha；, which are formed in the main body part 2； and a rubber material 4 attached to an opening 2c formed in the main body part 2 for partitioning between the inside and the outside of the internal flow passage &alpha；. The mixed injection member 1 can collect the blood in the internal flow passage &alpha； through the rubber material 4 and inject other fluid into the internal flow passage &alpha；. The introduction flow passage A is extended while being gradually reduced in diameter toward a position deviated from a center P of the internal flow passage &alpha；.【課題】内部流路の液体の採取や当該内部流路に対する液体の注入を円滑に行わせることができるとともに、内部流路における液体の滞留を確実に防止することができる混注部材を提供する。【解決手段】血液が流通する血液回路に接続可能な本体部２と、該本体部２内に形成され、血液回路の液体が流通し得る内部流路αと、本体部２内に形成され、内部流路αに血液を導入する導入流路Ａ及び内部流路αの血液を導出する導出流路Ｂと、本体部２に形成された開口部２ｃに取り付けられ、内部流路αの内部と外部とを仕切るゴム材４とを具備し、ゴム材４を介して内部流路αの血液を採取又は当該内部流路αに他の液体を注入可能な混注部材１において、導入流路Ａは、内部流路αの中心Ｐからずれた位置に向かって漸次縮径しつつ延設されたものである。【選択図】図３
