  We consider electric-magnetic duality(S-duality) in IIB matrix model with a
D3-brane background. We propose the duality transformation by considering that
of noncommutative Yang-Mills theory(NCYM) in four dimension. NCYM derived from
the matrix model has a Yang-Mills coupling related to the noncommutativity of
the spacetime. We argue that open strings bits as bi-local fields on the
spacetime are decoupled from the bulk in NCOS decoupling limits as it is in
string theory approach. We also discuss how our four dimensional spacetime
relates to higher, by applying the decoupling and the commutative limits of the
backgrounds of the matrix model.
