Abstract: The present invention relates to a hollow fiber type ultrafiltration membrane comprising a material of polymethyl methacrylate series in which no crosslinking is formed substantially and a process for its preparation. By employing adequate conditions, this material which is easy to handle makes it possible to achieve a steady manufacturing process and a constant quality of product. The obtained membrane is excellent in selective permeability and bio-compatibility, and expected to show its effect mainly in medical applications such as separation of plasma.