Kapachi Street Cloud is the interesting cloud line generated just over the Kanpachi Street on the west side of Tokyo metropolitan area under calm and clear atmospheric conditions in summer. The horizontal scale of this cloud line is less than 1km, which is smaller than meso-scale and larger than micro/canopy scale. This study tries to simulate this meso-micro scale urban cloud under the realistic meteorological conditions by using RAMS coupled with detailed geographical data ( including the distribution of anthropogenic heat emission) . ECMWF 0.5 objective analysis data were assimilated by nudging method, and a total of four kinds of different scale grids were nested ( the largest grid had 10km horizontal resolution and smallest 200m ). The results of wind field, vertical profiles of atmospheric variables ( temperature , humidity) and Kanpachi Street Cloud predicted by the model agree well with those of the observation by Kai et al.(1994) . The sensitivity of topography, artificial heat emission,and ground surface parameterization on the cloud formation were also discussed by numerical experiments, and following results were obtained ; (1) the convergence of two see-breeze flows, one from Tokyo Bay and another from Sagami Bay, is an essential mechanism to make the cloud line near the Kanpachi Street, and Kanpachi street itself does not have any direct effect to the cloud formation, (2) topography and distribution of artificial heat emission make effect to the position of cloud line, and (3) not only the sensible heat, but also the artificial latent heat mainly emitted by air conditioner of office buildings such as observed in Ginza city ( kanda et al,1996) should be included to the ground surface parameterization in urban area.