  Deformation-induced lateral migration of a bubble slowly rising near a
vertical plane wall in a stagnant liquid is numerically and theoretically
investigated. In particular, our focus is set on a situation with a small
clearance $c$ between the bubble interface and the wall. Motivated by the fact
that experimentally measured migration velocity (Takemura et al. (2002, J.
Fluid Mech. {\bf 461}, 277)) is higher than the velocity estimated by the
available analytical solution (Magnaudet et al. (2003, J. Fluid Mech. {\bf
476}, 115)) using the Fax\'{e}n mirror image technique for $\kappa(=a/(a+c))\ll
1$ (here $a$ is the bubble radius), when the clearance parameter
$\epsilon(=c/a)$ is comparable to or smaller than unit, the numerical analysis
based on the boundary-fitted finite-difference approach by solving the Stokes
equation is performed to complement the experiment. To improve the
understandings of a role of the squeezing flow within the bubble-wall gap, the
theoretical analysis based on a soft-lubrication approach (Skotheim & Mahadevan
(2004, Phys. Rev. Lett. {\bf 92}, 245509)) is also performed. The present
analyses demonstrate the migration velocity scales $\propto{\rm Ca}\
\epsilon^{-1}V_{B1}$ (here, $V_{B1}$ and ${\rm Ca}$ denote the rising velocity
and the capillary number, respectively) in the limit of $\epsilon\to 0$.
