The catheter assembly (10) comprises a protector (20) which covers at least the needle point (17) of the inner needle (16) during withdrawal of the inner needle (16). The protector (20) includes an arm inner cylinder containing (46) (42) engaging releasably from the outside to the proximal end of the catheter hub (14), the inner tube (42) is arranged on the inside, and the inner cylinder and a relative displaceable outer tube (62) axially relative to (42). In pulling operation of the inner needle (16), the needle tip of the inner needle (16) (17) moves backward relative to the protector outer cylinder after being housed in the (20) (62) of the inner cylinder (42), the arms (46) engages the arm (46) and catheter hub (14) is canceled by displacing outwardly.カテーテル組立体(10)は、内針(16)の抜去時に内針(16)の少なくとも針先(17)を覆うプロテクタ(20)を備える。プロテクタ(20)は、カテーテルハブ(14)の基端に外側から解除可能に係合するアーム(46)を含む内筒(42)と、内側に内筒(42)が配置され、且つ内筒(42)に対して軸線方向に相対変位可能な外筒(62)とを有する。内針(16)の抜去操作において、内針(16)の針先(17)がプロテクタ(20)に収容された後に外筒(62)が内筒(42)に対して後退移動すると、アーム(46)が外側方向に変位することでアーム(46)とカテーテルハブ(14)との係合が解除される。
