The present invention provides a technique which permits the withstand voltage measurement of a laminate web for capacitor layer manufactured by a continuous laminating method in a roll state wound around a core tube. The invention provides a roll of laminate for capacitor layer which is obtained by manufacturing a laminate web for capacitor layer by laminating a first electrically conductive layer, a dielectric layer and a second electrically conductive layer and winding this laminate web for capacitor layer from a start end side to a terminal end side thereof around a core tube. In the laminate web for capacitor layer 1a to be wound around the core tube 2, the in-plane laminating arrangement of the first electrically conductive layer 3, the second electrically conductive layer 5 and the dielectric layer 4 is contrived, and by superposing an insulating resin film F on one side of this laminate web for capacitor layer and simultaneously winding this insulating resin film to make the laminate web for capacitor layer in a roll state, whereby a roll of laminate web for capacitor layer for withstand voltage inspection in which electrical insulation between layers overlapping each other is formed. The invention also provides a method of performing withstand voltage inspection which involves partially removing interlayer dielectric means of the laminate web for capacitor layer 1a positioned in the periphery of the roll of laminate web for withstand voltage inspection and performing the inspection using the exposed first and second electrically conductive layers.