  Recent X-ray studies of starburst galaxies have found that Charge eXchange
(CX) commonly occurs between the outflowing hot plasma and cold gas, possibly
from swept-up clouds. However, the total CX flux and the regions where CX
occurs have been poorly understood. We present an analysis of the {\it
XMM-Newton} observations of M82, a prototype starburst galaxy, aiming to
investigate these key properties of the CX emisssion. We have used a blind
source separation method in the image analysis with the CCD data which
identified a component with the enhanced O-K lines expected from the CX
process. Analyzing the RGS spectra from the region identified by the image
analysis, we have detected a high forbidden-to-resonance ratio in the
\ion{O}{7} He$\alpha$ triplet as well as several emission lines from K-shell
transitions of C, N, and O enhanced in the CX process. The CX is less
responsible for the emission line of Ne and Mg and the accurate estimation of
the CX contribution is confirmed to be crucial in measuring chemical
abundances. The temperature of the plasma as electron receiver in the CX
process is significantly lower compared to that of the plasma components
responsible for most of the X-rays. From the low temperature and an estimation
of the CX emitting volume, we find that the CX primarily occurs in a limited
region at the interface of the plasma and gas whose temperature rapidly
decreases due to thermal conduction.
