PURPOSE: To provide a needle tip cap by which a used medical treatment needle can be scrapped safely and easily, and also, it does not cost, and it can be utilized for many kinds of needles, and a needle tip cap and an injector treating device for scrapping efficiently many medical treatment needles.

CONSTITUTION: This device is provided with a magazine 7 which can contain plural pieces of needle tip caps 6 having elasticity, which can pierce easily an injector 5, become integral with an injector 2 after piercing it and can be held. Also, this device is provided with a driving mechanism for driving to move this magazine 7, and when the needle tip cap 6 reaches coaxially an insertion guide part 3 of the injector in a determined position by following the movement of the magazine 7, the injector 5 is pierced into the needle tip cap 6 by inserting the injector 2 into the insertion guide part 3, and thereafter, the injector 2 and the needle tip cap 6 are scrapped integrally.