  The spin-averaged electromagnetic polarizabilities of the hyperons $\Lambda$
and $\Sigma$ are calculated within the one-loop approximation by use of the
dispersion theory. The photon and meson couplings to hyperons are determined so
as to satisfy the large N_c consistency condition. It is shown that in order
for the large N_c consistency condition to hold exotic hyperon states such as
$\Sigma^{**}$ with I=2 and J=3/2 are required in the calculation of the
magnetic polarizability of the $\Sigma$ state.
