  Long-term measurements of the radio flux density of Cassiopeia A relative to
Cygnus A have been carried out at 927 and 151.5 MHz. It was found the following
mean secular decrease rates of the radio emission of Cassiopeia A: $(0.72\pm
0.03)% \hbox{year}^{-1}$ at 927 MHz (for the period 1977--2002) and $(0.88\pm
0.09)% \hbox{year}^{-1}$ at 151.5 MHz (for the period 1980--2002). These values
of the secular decrease rate obtained over the period of the last 25 years are
substantially less than those of Baars et al. (1977). This indicates to the
slowing down of Cassiopeia A radio emission secular decrease. In addition to
this large scale time variation of Cassiopeia A flux density the measurements
have also shown a small scale (a few years) time variations over the smooth
secular decrease.
