To smooth a surface, to reduce anisotropy even in bending strength or the like and to enhance processability by using a sheet comprising a resin compsn. containing a thermoplastic polyester resin as a matrix as an intermediate layer and making glass cloths treated with a binder to be both surface layers.

A sheet comprising a resin compsn. containing a thermoplastic polyester resin as a matrix is used as an intermediate layer and glass cloths treated with a binder are set to both surface layers. As the thermoplastic polyester resin, PET is especially pref. Each of the pref. glass cloths has a thickness of 10-1000 μm, a fiber density of 200/inch or less and a use fiber denier of 20-1000 tex. As the binder, an epoxy resin especially pref. and the ratio of the binder in the cloths is pref. below 100 pts.wt. per 100 pts.wt. of the cloths. After the glass cloths are arranged and laminated on both surface layers, the whole is subjected to hot rolling. At this time, (the sum total of the thickness of the intermediate layer/that of both surface layers) is pref. 0.5-50.