The invention relates to a catheter insertion device comprising: an approximatelyhollow cylindrical catheter sleeve (2), at whose distal end a catheter (4) isattached； a needle sleeve (8) with a hollow needle (9), which is attached theretoand which, when ready for use, extends through the catheter sleeve (2) and thecatheter (4), and； a needle protective element (13) that is arranged inside thecatheter sleeve (2) while being able to move on the needle (9). Said needle protectiveelement has an engaging section (13c) that engages with an engaging device (9b),which is formed in the vicinity of the needle tip, when the hollow needle is withdrawnfrom the catheter sleeve (2). A check valve (7, 17) is placed inside the cathetersleeve (2) between the catheter (4) and the needle protective element (13). Thehollow needle (9), when ready for use, extends through said check valve, and thecheck valve automatically closes once the needle is withdrawn.
