  We show that the PAMELA anomaly in the positron fraction as well as the
ATIC/PPB-BETS excesses in the e^- + e^+ flux are simultaneously explained in
our scenario that a hidden U(1)H gauge boson constitutes dark matter of the
Universe and decays into the standard-model particles through a kinetic mixing
with an U(1)B-L gauge boson. Interestingly, the B-L charge assignment
suppresses an antiproton flux in consistent with the PAMELA and BESS
experiments, while the hierarchy between the B-L symmetry breaking scale and
the weak scale naturally leads to the right lifetime of O(10^26) seconds.
