We analyze rising motions of a bubble passing through array of particles by numerical simulations. Fluid-solid interaction is treated by an immersed boundary method (IBM) which is proposed by the present authors. The interaction force is incorporated into a 3rd order Runge-Kutta method in order to improve the numerical stability. Gas-liquid interfaces are captured by a volume of fluid (VOF) method with surface tension. A level set function is reconstructed from the volumetric fraction of fluid to evaluate the curvature of gas-liquid interfaces. Applications of these numerical improvements are validated through comparison with theoretical and experimental results. Also, it is found that the finite size effect of dispersed-phases on the rise velocity of the bubble is not negligible when diameter ratio of bubble to particle is relatively small.