  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.
