PURPOSE: To provide a composite water-absorbent sheet showing high water absorbability and holding strength even at the time of water absorption by laminating a crosslinked ethylene oxide polymer sheet irradiated with ionizing radiation or ultraviolet rays and a liquid-permeable sheet.

CONSTITUTION: An ethylene oxide polymer sheet is crosslinked by the irradiation with ionizing radiation or ultraviolet rays to be made insoluble. As other liquid- permeable sheet, a nonwoven fabric, paper or a perforated sheet is designated. A composite sheet is formed from the crosslinked ethylene oxide polymer sheet and the liquid-permeable sheet. When the ethylene oxide polymer sheet and the liquid-permeable sheet are directly laminated by thermal welding, the ethylene oxide polymer is crosslinked previously to lower in its thermal weldability and, therefore, the ethylene oxide polymer sheet is pref. laminated before crosslinking.