Dialyzer and method for manufacturing the same

1. A dialyzer comprising a substantially cylindrical case having a length M, a hollow fiber bundle made of a plurality of hollow fiber membranes provided in the case, a gap formed between an inner wall of the case and the hollow fiber bundle, a blood flow path formed by lumens of the hollow fiber membranes, a blood inlet to and a blood outlet from the blood flow path, a dialysate flow path formed by the gap between the inner wall of the case and the hollow fiber membranes and gaps between the hollow fiber membranes, a dialysate inlet to and a dialysate outlet from the dialysate flow path, and a cylindrical elastic tube having a length L inserted in the gap between the inner wall of the case and the hollow fiber bundle and substantially contacting the inner wall of the case,

wherein L is 5% to 90% of M;

a lubricant is provided between an outer surface of the elastic tube and the inner wall of the case;

a rib is formed on an outer circumferential surface of the elastic tube;

a concave portion for receiving the rib and fixing the elastic tube is formed on an inner wall of the case;

the rib is fitted into the concave portion so that the elastic tube is securely fixed in the case; and

the elastic tube is water-tightly contacted with the inner wall of the case by the elastic force of the tube, thereby securely fixing the elastic tube in the case.

2. A dialyzer according to claim 1 , wherein the cylindrical elastic tube comprises a plurality of elastic tubes.

3. A dialyzer according to claim 1 , wherein L is 10% to 80% of M.

4. A dialyzer according to claim 1 , wherein L is 20% to 60% of M.

5. A dialyzer according to claim 2 , wherein L is 10% to 80% of M.

6. A dialyzer according to claim 2 , wherein L is 20% to 60% of M.