  We present results from ASCA observations of the binary CI Cam both in
quiescence and in outburst in order to identify its central accreting object.
The quiescence spectrum of CI Cam consists of soft and hard components which
are separated clearly at aound 2-3keV. A large equivalent width of an iron Ka
emission line prefers an optically thin thermal plasma emission model to a
non-thermal power-law model for the hard component, which favors a white dwarf
as the accreting object, since the optically thin thermal hard X-ray emission
is a common characteristic among cataclysmic variables (binaries including an
accreting white dwarf).
  The outburst spectrum, on the other hand, is composed of a hard component
represented by a multi-temperature optically thin thermal plasma emission and
of an independent soft X-ray component that appears below 1 keV intermittently
on a decaying light curve of the hard component. The spectrum of the soft
component is represented well by a blackbody with the temperature of
0.07-0.12keV overlaid with several K-edges associated with highly ionized
oxygen. This, together with the luminosity as high as ~1E38 erg/s is similar to
a super-soft source (SSS). The outburst in the hard X-ray band followed by the
appearance of the soft blackbody component reminds us of recent observations of
novae in outburst. We thus assume the outburst of CI Cam is that of a nova, and
obtain the distance to CI Cam to be 5-17kpc by means of the relation between
the optical decay time and the absolute magnitude. This agrees well with a
recent estimate of the distance of 5-9kpc in the optical band. All of these
results from the outburst data prefer a white dwarf for the central object of
CI Cam.
