PROBLEM TO BE SOLVED: To provide a liquid injection component having few number of components, preventing residual blood and residual liquid of transfusion from being produced by saving the priming volume of the liquid, and capable of favorably circulating the liquid by substantially securing a flow path of the liquid.SOLUTION: The liquid injection component includes a communication member 1, a connection member 21, and a connecting tube 40. The connecting tube 40 is continuously and integrally formed with a large-diameter part 40B, an intermediate part 40M, a small-diameter part 40S, a flange 40F, and a connection part 40A, from a proximal end PE side to a distal end DE side. The communication member 11 is inserted into the proximal end PE side interior of the connecting tube 40 from the distal end DE side to the proximal end PE side. The communication member 11 covers all circumferences in the longitudinal direction at the proximal end PE side of the connecting tube 40.COPYRIGHT: (C)2014,JPO&INPIT【課題】部品点数が少なく、液体のプライミングボリュームを省力化し、血液の残血、輸液の残液等を生じることがなく、液体の流路を十分に確保して液体を流通させることができる液体注入部品を提供すること。【解決手段】連通部材1と接続部2と接続管40とを有する。接続管40は、基端PE側から末端DE側からにわたって、大径部40B、中間部40M、細径部40S、フランジ40F及び接続部40Aを連続して一体に形成している。連通部材11は、末端DE側から基端PE側に亘って、接続管40の基端PE側の内部に挿入している。連通部材11は、全ての長手方向の外周を接続管40の基端PE側で覆っている。【選択図】図2