  Littlest Higgs model predicts some extra particles beyond the Standard Model.
Among them, an extra neutral gauge boson A_H is lightest and its mass could be
a few hundred GeV. We study production and decay of A_H at future e^+ e^- inear
collider and compare them with those of Z' bosons in supersymmetric (SUSY) E_6
models. We find that, if the extra gauge boson mass is smaller than \sqrt{s} of
the linear collider, the forward-backward asymmetries of b- and c-quarks at the
A_H pole differ significantly from those given by the Z' bosons, and are useful
to test the littlest Higgs model and SUSY E_6 models.
