  We discuss a classical integrability in the type IIB string theory on the
AdS_5 x S^5 background. By using the Roiban-Siegel formulation of the
superstring on the AdS_5 x S^5, we carefully treat the Wess-Zumino term and the
constraint conditions intrinsic to the supersymmetric case, and construct
explicitly non-local charges for a hidden infinite-dimensional symmetry. The
existence of the symmetry is shown by Bena-Polchinski-Roiban. Then the super
Yangian algebra is calculated. We also show the Serre relation ensuring the
structure of the Hopf algebra. In addition, the classical integrability is
discussed by constructing the Lax pair and the transfer matrix.
