  We propose a scenario of dark sector described by a hidden $SU(2)$ gauge
symmetry which is broken by a vacuum expectation value(VEV) of a scalar
multiplet. We discuss a general mass relation among $SU(2)$ gauge bosons after
spontaneous symmetry breaking which is determined by weight of gauge group
representation associated with a scalar multiplet developing VEV. Then a model
with quintet and triplet scalar fields is discussed in which hidden gauge boson
can be dark matter(DM) stabilized by remnant discrete $Z_2$ symmetry and
resonant dark matter annihilation is realized by mass relation between DM and
mediator. We estimate relic density and spin independent DM-nucleon scattering
cross section searching for allowed parameter region.
