Vertex Operators for Super Yang-Mills and Multi D-Branes in Green-Schwarz Superstring

We study vertex operators for super Yang-Mills and multi D-branes in covariant form using Green-Schwarz formalism. We introduce the contact terms naturally and prove space-time supersymmetry and gauge invariance. The nonlinear realization of broken supersymmetry in the presence of D-branes is also discussed. The shift of fermionic coordinate \delta^{(-)}\Psi =\eta becomes exact symmetry of D-brane in the static gauge, where $\eta$ is a constant spinor in U(1) direction.