  We propose a seesaw model with a hidden gauge symmetry $SU(2)_H \times
U(1)_X$ where two types of standard model singlet fermions in realizing a
seesaw mechanism are organized into $SU(2)_H$ doublet. Then we formulate scalar
and gauge sector, neutrino mass matrix and lepton flavor violations. In our
gauge sector, $Z$-$Z'$ mixing appears after spontaneous symmetry breaking and
we investigate constraint from $\rho$-parameter. In addition we discuss $Z'$
production at the large hadron collider via $Z$-$Z'$ mixing, where $Z'$ tends
to dominantly decay into heavy neutrinos.
