  We study an anisotropic scale transformation in the worldsheet description of
D3-branes in Type IIB theory, and show that the transformation is really a
symmetry in a region near D3-branes. AdS/CFT correspondence follows from this
symmetry. We will explicitly show that Wilson loops in N=4 supersymmetric
Yang-Mills theory and minimal surfaces in AdS_5 are related by the symmetry.
The functional form of a supersymmetric Wilson loop operator is naturally
derived from our worldsheet point of view.
