It is an object of the present invention to provide an injection needle protector, an injection needle unit, and an injector to which this injection needle unit is mounted, with which the needle tip of an injector can be accurately inserted into a drug container without making a drug mixing apparatus more complicated. An injection needle protector 1 that protects a needle tube 9 connected to a needle base 13 by covering the needle tube 9 comprises a first cap 5 that protects the needle tube 9 on the needle base 13 side and is also held by an injector holder, and a second cap 7 that protects the rest of the needle tube 9 that is not protected by the first cap 5. The first cap 5 has a supporter 11 that supports the needle tube 9 from the outer periphery.
