TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The graft ratio of hydrophilic ethylenic unsaturated group-containing monomer is 0.01-50%. The hydrophilic ethylenic unsaturated group-containing monomer having phosphorylcholine group is methacryloyl oxyalkyl phosphorylcholine and/or acryloyl oxyalkyl phosphorylcholine of formula: CH2=C(R1)-C(=O)-O-(CH2)n-O-P(=O)(O-)-O-(CH2)2-N+(CH3)3, preferably 2-methacryloyl oxyethyl phosphorylcholine.R1=H or methyl;andn=2-10.    TECHNOLOGY FOCUS - POLYMERS - Preferred Properties: The sintered compact has average porosity of 20-60 volume%. The average diameter of pores of porous sintered compact is 1-150 mu m. The polyolefin resin particles have viscosity average molecular weight of 50000-7 million, volume density of 0.20-0.55 g/cm3, density of 0.850-0.970 g/cm3, average particle diameter of 10-350 mu m, and contain 90 weight% or more of particles with size of 1-500 mu m. The sintered compact has water droplet absorption time of 30 seconds or less (after removing 60 degrees C warm water soluble components), and water sucking height of 5 mm or more in 1 minute. Preferred Particles: The polyolefin resin particles contain homopolymer of ethylene, or copolymer of ethylene and 3C or more olefin. EXAMPLE - A flat sintered compact was formed using high-density polyethylene powder having average particle diameter of 277 mu m, viscosity average molecular weight of 300000, volume density of 0.45 g/cm3 and density of 0.955 g/cm3. The sintered compact was immersed in solution containing benzophenone (1 g) dissolved in acetone, and dried under reduced pressure for 1 hour. The processed sintered compact was fixed in an aqueous solution of 2-methacrolyl oxyethyl phosphorylcholine, and ultraviolet-ray was irradiated for 90 minutes. Then, the compact was washed using distilled water at 25 degrees C for 8 hours for 3 times, and dried. Thus, hydrophilic porous sintered compact with graft ratio of 0.40% was obtained. A humidification element was formed using the obtained hydrophilic porous sintered compact. The humidification element had long-term sustainability of water absorption function, excellent moldability, impact resistance, mechanical strength, and dimensional stability during water absorption.