  We study local operators of U(N)xU(N) N=6 Chern-Simons-matter theory
including a class of magnetic monopole operators. To take into account the
interaction of monopoles and basic fields for large Chern-Simons level k, we
consider the appropriate perturbation theory in 1/k which reliably describes
small excitations around protected chiral operators. We also compute the
superconformal index with some simple monopole operators and show that it
agrees with the recent result obtained from localization. For this agreement,
it is crucial that excitations of gauge fields and some matter scalars mix,
which is described classically by odd dimensional self-duality like equations.
