A needle safety device (12) for a medical device, in particular for an IV catheter assembly (10), being movably arranged on the needle (24) comprising: a first part (42) made of a suitable plastic material； a second part (44) preferably made of a strip of suitable metal sheet； and a ring (46) surrounding the said first part (42) and said second part (44) having elastic properties made of suitable elastomeric material. The invention also relate to an IV catheter assembly (10), comprising:a catheter housing (14) having a proximal section (26) and a distal section (28), wherein the proximal section (26) is joined to the catheter tube (16) and the proximal section (26) defines an enclosure (30) to retain therein the needle safety device (12) prior to use； wherein the said needle safety device (12) is removable from the said enclosure (30) in the said catheter housing (14) once the needle tip (36) is received in the said needle safety device (12) upon withdrawal of the needle (24) from the said catheter tube (16). [Fig. 6 (a)]
