The present invention relates to a hydrophilized membrane which has greatly suppressed adhesion of blood cells such as erythrocytes, leukocytes and blood platelets within blood, by easily conducting hydrophilization of a hydrophobic porous membrane, and a process for the hydrophilization. The present invention relates to a hydrophilized hydrophobic porous membrane which is obtained by impregnating a medical supply of which the part which comes into contact with blood is hydrophobic in a solution of a substance having surface activity, then rinsing in a solvent into which the surfactant is soluble, and adsorbing an extremely small amount of the substance having surface activity to the surface of the part which comes into contact with blood, wherein the adhesion of blood cells such as erythrocytes, leukocytes and blood platelets within blood is greatly suppressed. The present invention also relates to a process for hydrophilization.