  The role of the suppression of the coupling constant in the pseudovector
pion-nucleon interaction is examined to account for the calculation of the
magnetic moment of nucleon. Among three kinds of the higher-order corrections
the vacuum polarization of the pion propagator contributes to the numerical
value considerably. On the other hand the lowest-order vertex correction for
the pion-nucleon-nucleon vertex does not give large effect in the approximation
of the on-shell momenta for nucleons.
