The present paper was concerned with a part of series of the numerical study on the flow in a two-dimensional rough wall channel by authors. On the flow through a two-dimensional channel with repeated squre ribs, the Navier-Stokes equations were solved by the finite difference method. The several flow cases for the pitch ratio W/h=2～11 (W and h denote the roughness spacing and height, respectively) and the Reynolds number Re=5～3000 were calculated. In order to reserach the effect of wall roughness on the flow pattern over the rough wall surface, the velocity distributions were presented in this paper. As the results, the velocity distribution near the wall showed the periodic flow pattern in the similitude of roughness geometry, and its flow pattern became indistinct with increasing the distance from the wall surface. The distance from the wall surface to the location of indistinct periodic flow pattern depended on both the pitch ratio and the Reynolds number. It was noticeable results that the vortex pattern in the roughness groove was closely related with this distance of indistinct periodic flow pattern.