In this paper the influence of roughness of electrode surface on the ozone generation by the silent discharge are described. The experiments are carried out to clarify the effect of electrode surface on the discharge current, ozone yield, ozone yield efficiency and the distribution of microdischarges. The ozonizer used consists of a parallel-plane electrode contacted with dielectric films. On the surface of electrodes, ditches are worked mechanically at an angle of 60 degrees like a mesh. The depth and pitch of the ditches are varied as parameters of the surface conditions. The results obtained are as follows. As the depth is deep and the pitch is small, both the discharge current and ozone yield decrease. But, ozone yield efficiency increases to the contrary. The reason why ozone yield efficiency is influenced by the electrode surface is that the discharge current depends on the electrode flat-area rate of ditched electrodes. When the electrode flat-area rate is small. the ozone yield efficiency increases. Under this surface condition, the discharge luminous quantity is small. However, a large number of microdischarge columns take place, as compared with the plane electrode. Therefore, the discharge space becomes uniform. As a result, this electrode surface condition is effective to improve the efficiency of ozonizers.