There is provided an injector having an improvement in a linear launching profile. The injector of the present invention is used for launching a lancet to provide a pricking. The injector of the present invention comprises a plunger capable of launching the lancet in a pricking direction, an injector housing which surrounds the plunger, and an injector cap capable of being attached and detached with respect to the injector housing. In particular, an inner face of the injector cap is provided with a rib, and the rib and the plunger moving for the pricking are capable of contacting with each other.
