An object of the present invention is to provide a polysulfone hemodialyzer with large membrane area that exhibits an unprecedented high dialytic performance over a wide molecular weight range from urea to ² 2 -microglobulin. There is provided a polysulfone hemodialyzer having a membrane area of >2.4 but‰ 3.2 m 2 and a dialysate rectifying portion with specified broadening at end portion of bundle, the polysulfone hemodialyzer achieves the above object.
