Is pen ink good to use for tattoo?

Quite simply, NO! This is ink that is toxic when introduced to the bloodstream, not that you should be going that deep to begin with, but you are never to use this kind of ink. If you for whatever reason can't get your hands on real tattoo ink and real materials, at least use India Ink. The results will look quite clearly home done and will probably fall out for the most part while healing, but it is at least non-toxic to you.