A polymer sheet (4) is so configured that an upper layer sheet (10) and a lower layer sheet (11) are bonded to each other through first bond parts (13) which are arranged in a houndstooth-like pattern and second bond parts (14) each of which is located at a halfway point on an oblique line that connects any two of four first bond parts respectively located on the right side and the left side and at the top and the bottom of the corresponding second bond part. The polymer sheet (4) is partitioned into: multiple first partitioned regions (15), each of which is surrounded by both of the bond parts (13) and (14), and which are arranged in a positive grid-like configuration, and each of which has, enclosed therein, a highly water-absorbable polymer (12) and second partitioned regions (16), each of which is positioned at the center of adjacent four pieces of the first partitioned regions (15), and four oblique directions of each of which are surrounded by the second bond parts (14). The bonding strength of each of the second bond parts (14) is set to a value that is smaller than that of each of the first bond parts (13), and the bonding at the second bond parts (14) is detached preferentially to the bonding at the first bond parts (13) when a highly water-absorbable polymer (12) absorbs a liquid and is swollen.
