  The concept of the quantum Pfaffian is rigorously examined and refurbished
using the new method of quantum exterior algebras. We derive a complete family
of Pl\"ucker relations for the quantum linear transformations, and then use
them to give an optimal set of relations required for the quantum Pfaffian. We
then give the formula between the quantum determinant and the quantum Pfaffian
and prove that any quantum determinant can be expressed as a quantum Pfaffian.
Finally the quantum hyper-Pfaffian is introduced, and we prove a similar result
of expressing quantum determinants in terms of quantum hyper-Pfaffians at
modular cases.
