  We formulate N=4 supersymmetric Yang-Mills theory in terms of soft-collinear
effective theory. The effective Lagrangian in soft-collinear effective theory
is developed according to the power counting by a small parameter \eta \sim
p_{\perp}/Q. All the particles in this theory are in the adjoint representation
of the SU(N) gauge group, and we derive the collinear gauge-invariant
Lagrangian in the adjoint and fundamental representations respectively.
  We consider collinear and ultrasoft Wilson lines in this theory, and show the
ultrasoft factorization of the collinear Lagrangian by redefining the collinear
fields with the use of the ultrasoft Wilson lines. The vertex correction for a
vector fermion current at one loop is explicitly presented as an example to
illustrate how the computation is performed in the effective theory.
