In the 1st report, we reported on the experimental results regarding to heat transfer at the surface of smooth flat plate in forced flow. In this report, we report on the results of experiments on rough plate. It is thought that the effect of roughness on surface heat transfer, is varied by height, depth, pitch and shape of roughness elements. At first, we experimented on the effect of the pitch of elements of roughness. Roughness of surface is given by making the parallel grooves that is perpendicular to flowing direction. In the case of flat front edge plate, the special turbulent boundary layer was seen in any position over certain Reynolds'Number, and in its range, Nu/Re was constant in any Re. And the value of Nu/Re was maximum in the case of a certain pitch for grooved plate with same depth, where Nu is Nusselt's Number and Re is Reynolds's Number.