Abstract: There is provided a hollow fiber membrane module (1) comprising: a membrane bundle (20) of a plurality of hollow fiber membranes (10); a cylindrical body (30) housing the membrane bundle (20); a fixing portion (40, 50) in which at least one end of the membrane bundle (20) is fixed to the cylindrical body (30); and a raw water outflow nozzle (34) for allowing raw water to flow out from the vicinity of the fixing portion (40). Raw water supplied into the cylindrical body (30) is allowed to permeate from the outside into the inside of each hollow fiber membrane (10). A soft potting portion (42) has, in its surface to be in contact with raw water, at least one groove (43).