PURPOSE: To reduce the generation of warpage due to heating at the time of processing by setting the heat shrinkage factor after heating and pressing in a copper foil layer to a specific ratio with respect to that of the layer opposite to the copper foil layer in the constitution of a prepreg.

CONSTITUTION: In the production of a single surface copper clad laminated sheet, the constitution of a prepreg is set so that the heat shrinkage factor after heating and pressing of a copper foil layer is set to 25-75%, pref., 30-70% with respect to that of the layer opposite to the copper foil layer. The heat shrinkage factor is a value calculated from dimensions before and after heating when a laminate with a thickness of 1.6mm obtained by heating and pressing eight superposed prepregs of the same kind is heated to 150°C at a speed of 5°C/min and subsequently naturally cooled according to a prescribed formula.