  We present the results of optical photometry of the recurrent nova CI Aql in
later phase of the outburst which occurred in 2000. Our observation revealed
that the object reached the quiescent level between 2001 December and 2002
April and therefore that CI Aql is a unique recurrent nova characterized by an
extremely long (1.4--1.7 yr) plateau phase. The light curve obtained in the
outburst suggests that the object is the first example of an intermediate
between classical novae and recurrent novae. In comparison with estimation
given in published theoretical calculations, the long duration of the plateau
phase supports a higher hydrogen content of the white-dwarf envelope, while
such an abundance of hydrogen requires a later cessation of the wind which is
in disagreement with the sudden fading observed in late November of 2000. The
light curve obtained in later phase of the outburst indicates that the object
was fainter and the gradual decline was steeper than predicted. These
discrepancies between the observation and theoretical prediction require
drastic modification of the present model of CI Aql.
