A process for manufacturing a multilayer flexible wiring board, which allows individual layers of wiring boards to be precisely positioned and to be readily stacked. A mask for exposure is prepared in which a plurality of pattern holes corresponding to individual layers of wiring boards of a multilayer flexible wiring board are arranged in the direction perpendicular to the transporting direction P of substrate. This mask for exposure is used to form a plurality of wiring patterns corresponding to individual layers of wiring boards of a multilayer flexible wiring board on the same sheet-like substrate.