  We revisit constraints on small-scale primordial power from annihilation
signals from dark matter minihalos. Using gamma rays and neutrinos from
extragalactic minihalos and assuming the delta-function primordial spectrum, we
show the dependence of the constraints on annihilation modes, the mass of dark
matter, and the annihilation cross section. We report both conservative
constraints by assuming minihalos are fully destructed when becoming part of
halos originating from the standard almost-scale invariant primordial spectrum,
and optimistic constraints by neglecting destruction.
