  We investigate the possibility that the W+4 jets background is a source of
the anomalously large top-antitop (t\={t}) charge asymmetry observed at the
Tevatron. We simulate the t\={t} reconstruction of the signal and background
events at the matrix-element level and find that the reconstructed t\={t}
candidates from the W +4 jets background could give large forward-backward
asymmetry. We suggest serious re-evaluation of the W+4 jets background for the
t\={t} candidate events by studying the distributions of the reconstructed
t\={t} systems in their rapidity difference, the transverse momentum of the top
quark, and that of the t\={t} system, which can differ significantly from those
of the QCD t\={t} production events especially at high t\={t} invariant mass.
