  A new type of gravitational microlensing experiment toward a field where
stars are not resolved is being developed observationally and theoretically:
pixel lensing. When the experiment is carried out toward the M31 bulge area,
events may be produced both by Massive Compact Halo Objects (MACHOs) in our
Galactic halo and by lenses in M31. We estimate that $\sim 10-15\%$ of the
total events are caused by Galactic halo MACHOs assuming an all-MACHO halo. If
these Galactic events could be identified, they would provide us with an
important constraint on the shape of the halo. We test various observables that
can be used for the separation of Galactic halo/M31 events. These observables
include the Einstein time scale, the effective duration of an event, and the
flux at the maximum amplification, but they cannot be used to separate each
population events. However, we find that most high maximum-flux Galactic halo
events can be isolated through a satellite-based measurement of the flux
difference caused by the parallax effect. For the detection of the flux
difference, it is required to monitor events with an exposure time of $\sim 20\
{\rm min}$ by a 0.5 m telescope mounted on a satellite. Such observations could
be carried out as a minor component of a mission aimed primarily at events seen
toward the Galactic bulge and Large Magellanic Cloud. In addition, proper
motion can be used to isolate Galactic halo/M31 events, but only for $\sim 5\%$
of high signal-to-noise ratio M31 events and only 1\% of Galactic halo events.
