  We construct the Picard-Fuchs equations of the $N=2$ supersymmetric $SU(2)$
gauge theories with $N_f=0,1,3$ matter multiplets. For the $N_f=0$ theory from
the solutions of the Picard-Fuchs equation the monodromy matrices on the
quantum moduli space are determined. We analyze the Seiberg-Witten solutions to
compute monodromies exactly and present the instanton expansion of the periods
for the $N_f=0,3$ theories.
