The present invention is a needle unit to be attached to a syringe for medical use, which is a needle member having an internal space along the longitudinal direction, comprising a needle hole formed in a side surface of a distal end portion, A needle member that communicates with the outside via a needle hole and an opening, and a needle member that supports the proximal end portion of the needle member and is attached to the syringe, whereby the internal space of the syringe and the needle member A base portion which is movable along the outer peripheral surface of the needle member and is movable between a first position at which the needle hole is closed and a second position where the needle hole is opened at the base end side beyond the first position 2, an urging member for urging the slide member from the second position side to the first position side, a cap removably attached to the base portion so as to cover the needle member .本発明は、医療用のシリンジに装着される針ユニットであって、長手方向に沿う内部空間を有する針部材であって、先端部の側面に形成された針穴、及び基端部に形成された開口を有し、内部空間は針穴及び開口を介して外部に連通する、針部材と、針部材の基端部を支持するとともに、シリンジに取付けられることで、シリンジと針部材の内部空間とを連通させる基台部と、針部材の外周面に沿って移動可能で、少なくとも、針穴を閉じる第1の位置と、第1の位置よりも基端部側において針穴を開放する第2の位置とをとり得るスライド部材と、スライド部材を第2の位置側から第1の位置側へ付勢する付勢部材と、針部材を覆うように基台部に着脱可能に取付けられるキャップと、を備えている。
