The needle assembly 1 includes a holder 2 for accommodating a sampling container for blood in a storage space S, a distal needle portion 3 a having a puncture portion formed at a distal end portion thereof, and a distal needle portion 3 a communicating with the distal needle portion and at a rear end portion A rear end side needle portion 3b in which the formed puncture portion is positioned in the accommodation space, and a rear end side needle portion 3b which covers the rear end side needle portion and deforms when the sampling container is accommodated in the accommodation space, And a sleeve 4 penetrated by the part. A blood confirming space 13 (flashback space) is formed in the holder 2, and the blood confirming space and the external space are partitioned by a membrane 14 which has air permeability but does not allow liquid to pass therethrough, and the front end side needle And a flow path g for communicating the section and the blood confirmation space are provided. It is possible to easily confirm that the distal needle portion has been inserted into the blood vessel.針組立体1は、収容空間Sに血液の採取容器を収容するホルダー2と、先端部に穿刺部が形成された先端側針部3aと、当該先端側針部と連通するとともに後端部に形成された穿刺部が上記収容空間内に位置した後端側針部3bと、当該後端側針部を覆うとともに上記採取容器が上記収容空間に収容されると変形して上記後端側針部によって貫通されるスリーブ4とを備えている。 上記ホルダー2に血液確認用空間13(フラッシュバック用空間)を形成するとともに、当該血液確認用空間と外部空間とを通気性を有するものの液体を通過させない膜14で区画し、さらに上記先端側針部と上記血液確認用空間とを連通させる流路gを設ける。 先端側針部が血管に挿入されたことを容易に確認することができる。
