  The intensity of low frequency gravitational waves from black hole MACHO
binaries is studied. First we estimate the gravitational wave background
produced by black hole MACHO binaries in the Milky Way halo as well as the
cosmological gravitational wave background produced by the extragalactic black
hole MACHO binaries. It is found that the cosmological gravitational wave
background due to black hole MACHO binaries is larger than the halo background
unless an extreme model of the halo is assumed, while it is smaller than the
background due to close white dwarf binaries at $\nu_{gw} \siml 10^{-2.5}$ Hz
if the actual space density of white dwarfs is maximal. This cosmological
background due to black hole MACHO binaries is well below the observational
constraints from the pulsar timing, quasar proper motions and so on. We find
that one year observation by LISA will be able to detect gravitational waves
from at least several hundreds of nearby independent black hole MACHO binaries
whose amplitudes exceed these backgrounds. This suggests that LISA will be able
to pin down various properties of primordial black hole MACHOs together with
the results of LIGO-VIRGO-TAMA-GEO network. Furthermore, it may be possible to
draw a map of the mass distribution of our halo, since LISA can determine the
position and the distance to individual sources consisted of black hole MACHO
binaries. Therefore, LISA may open a new field of the gravitational wave
astronomy.
