  We discuss N=2 SU(2) Yang-Mills gauge theories coupled with N_f (=2,3)
massive hypermultiplets in the weak coupling limit. We determine the exact
massive prepotentials and the monodromy matrices around the weak coupling
limit. We also study that the double scaling limit of these massive theories
and find that the massive N_f -1 theory can be obtained from the massive N_f
theory. New formulae for the massive prepotentials and the monodromy matrices
are proposed. In these formulae, N_f dependences are clarified.
