The present invention provides a glass cloth suitable for producing a printed wiring board to be used in the electronics and electric fields, which has small anisotropy in dimensional change and is free from warpage and twist, a prepreg using said glass cloth, and a printed wiring board using said glass cloth. The glass cloth relevant to the present invention is characterized in that the warp yarn and the weft yarn are configured with a glass yarn of 1.8×10−6 kg/m to 14×10−6 kg/m, a (breadth/length) ratio of an average filament diameter of said weft yarn to an average filament diameter of said warp yarn is 1.01 or more but less than 1.27, and a thickness is 10 μm to 40 μm.