Recently, we proposed microchannel (MC) emulsification, a novel method for making monodispersed emulsion with a coefficient of variation of less than 5%. In this study, we prepared monodispersed polymeric divinylbenzene microspheres (MS) exceeding 50 mum in diameter by MC emulsification and subsequent polymerization. Using two types of MC plates, we prepared MS with 86.7 mum on average diameters and 4.8% coefficients of variation, as well as MS with 69.0 mum on average diameters and 4.1% coefficients of variation. The MS diameter can be controlled by the terrace length. The MS prepared in this manner had as narrow a size distribution as did the MS prepared by seed polymerization. The effects of the applied pressures on the droplet diameter distributions during MC emulsification were investigated, At low applied pressures, the applied pressure did not affect the droplet diameter so much, and monodispersed emulsions were produced.