To provide a collected initial blood flow removal bag and a collected initial blood flow removal set, capable of collecting blood without sucking air in a vacuum blood collection tube even if reversing the collected initial blood flow removal bag.

This collected initial blood flow removal bag BE or BF for accumulating the initial-flow blood collected from a donor is so formed that a bag body 21 is formed with an inlet 23 for the initial-flow blood and an outlet 24 for the initial-flow blood; the inside of the bag body 21 is formed with a first partition part P1 and a second partition part P2 to partition the inside of the bag body 21 into a blood reservoir S1 and an air accumulator S2, and is formed with a blood passage W1 and an air passage W2; and the outside of the bag body 21 is equipped with a closing means C capable of closing the blood passage W1 and the air passage W2.