  A $q$-deformation of the middle convolution was introduced by Sakai and
Yamaguchi. We apply it to a linear $q$-difference equation associated with the
$q$-Painlev\'e VI equation. Then we obtain integral transformations. We
investigate the $q$-middle convolution in terms of the affine Weyl group
symmetry of the $q$-Painlev\'e VI equation. We deduce an integral
transformation on the $q$-Heun equation.
