  We report the results of fluctuation analysis of the off-source field from
the 1 Million second Chandra observation of the Hubble Deep Field-North
(HDF-N). The distribution of the counts in cells has been compared with the
expectations from the Log N - Log S model to constrain the behavior of the
source number density down to a factor of several lower than the
source-detection limit. Our results show that the number counts in the soft
band (0.5-2 [keV]) continue to grow down to Sx = 7e-18 [erg s^{-1} cm^{-2}],
possibly suggesting the emergence of a new population and agree well with a
prediction of star forming galaxies by Ptak et al. (2001). For the hard band
(2-10 keV), the fluctuation analysis can loosely constrain the source counts
fainter than the detection limit and we found an upper limit of 10000 [srcs
deg^{-2}] at Sx=2e-16 [erg s^{-1}cm^{-2}].
