  In this paper, the late-time optical photometry of supernova (SN) 1993J in
M81 from Feburary 1995 to Janurary 2003 is presented. The observations were
performed in a set of intermediate-band filters that have the advantage of
tracing the strength variations of some spectral features. SN 1993J was found
to fade very slowly at late times, declining only by $0.05\pm0.02$ mag 100
d$^{-1}$ in most of the filters from 2 to nearly 10 yrs after discovery. Our
data suggest that the circumstellar interaction provides most of the energy to
power the late-time optical emission of SN 1993J. This is manifested by several
flux peaks seen in the rough spectral energy distributions constructed from the
multicolor light curves. The flux peaks near 6600 \AA, 5800 \AA{} and 4900
\AA{} may correspond to the emission lines of H$\alpha$, Na I D + He I
$\lambda$5876 and [O III] $\lambda\lambda$4959, 5007, respectively. The
evolution of these emission lines suggest a power-law SN density model as
proposed by \citet{cf94}.
