  We study the N=1 U(N) gauge model obtained by spontaneous breaking of N=2
supersymmetry. The Fayet-Iliopoulos term included in the N=2 action does not
appear in the action on the N=1 vacuum and the superpotential is modified to
break discrete R symmetry. We take a limit in which the Kahler metric becomes
flat and the superpotential preserves non-trivial form. The Nambu-Goldstone
fermion is decoupled from other fields but the resulting action is still N=1
supersymmetric. It shows the origin of the fermionic shift symmetry in N=1 U(N)
gauge theory.
