To provide a method and apparatus for manufacturing a fluid separation membrane element which make the relative position of a stock solution flow passage material with respect to the separation membrane settable with high accuracy.

The method and aperture of forming a separation membrane unit 22 by setting the separation membrane 20 of a prescribed length at a prescribed position, drawing out or delivering the stock solution flow passage material 9 from a stock solution flow passage material roll body 10, cutting the material at the prescribed length, setting the material at a regulated position P and placing the stock solution flow passage material 90 atop the separation membrane 20, in which the stock solution flow passage material 9 is once drawn out or delivered to the position deviating from the regulated position P and is cut and thereafter the material is transferred to the regulated position P and is then placed atop the separation membrane 20.