  The Massless Thirring model associated with SO(5) is solved in terms of the
local U(1) symmetry. The local U(1) symmetry is related to q-deformation of
four-component field operators due to the nonlinear interaction for differently
internal degree of freedom. The Bethe ansatz wavefunction is also discussed. In
addition, the local U(1) symmetry in the Yangian associated with
SO(5)(Y(SO(5))) is explored.
