  We study our Schwinger-Dyson equation as well as the large $N_{c}$ loop
equation for supersymmetric Yang-Mills theory in four dimensions by the N=1
superspace Wilson-loop variable. We are successful in deriving a new manifestly
supersymmetric form in which a loop splitting and joining are represented by a
manifestly supersymmetric as well as supergauge invariant operation in
superspace. This is found to be a natural extension from the abelian case. We
solve the equation to leading order in perturbation theory or equivalently in
the linearized approximation, obtaining a desirable nontrivial answer. The
super Wilson-loop variable can be represented as the system of one-dimensional
fermion along the loop coupled minimally to the original theory. One-loop
renormalization of the one-point Wilson-loop average is explicitly carried out,
exploiting this property. The picture of string dynamics obtained is briefly
discussed.
