\documentstyle[a4j]{j-article}
\begin{document}
%
\begin{equation}
\label{kakezan}
 \left(
  \begin{array}{c}
   b_{1} \\
   b_{2} \\
   b_{3} 
  \end{array}
 \right)
=
 \left[
  \begin{array}{ccc}
   a_{11} & a_{12} & a_{13} \\
   a_{21} & a_{22} & a_{23} \\
   a_{31} & a_{32} & a_{33}
  \end{array}
 \right]
%
 \left(
  \begin{array}{c}
   x_{1} \\
   x_{2} \\
   x_{3} 
  \end{array}
 \right)
\end{equation}
%
\end{document}
%