  Discrete Lotka-Volterra equation over $p$-adic space was constructed since
$p$-adic space is a prototype of spaces with the non-Archimedean valuations and
the space given by taking ultra-discrete limit studied in soliton theory should
be regarded as a space with the non-Archimedean valuations in the previous
report (solv-int/9906011). In this article, using the natural projection from
$p$-adic integer to a ring $Z/p^n Z$, a soliton equation is defined over the
ring. Numerical computations shows that it behaves regularly.
