A sheet-like absorber which has an absorbent polymer mixed into a fiber layer formed from heat fusible fibers and expands by absorbing liquid, the absorber comprising a groove portion that is formed along the entire length of one sheet surface and extends along the sheet longitudinal direction, a first absorbent layer that forms the other sheet surface, and a plurality of second absorbent layers which form the one sheet surface and is stacked on the first absorbent layer spaced apart in the sheet width direction, wherein the groove portion is formed by opposing surfaces of adjoining second absorbent layers and the surface of the first absorbent layer, the first absorbent layer and second absorbent layers are fiber layers formed from heat fusible fibers with an absorbent polymer mixed into the fiber layers, the content of the absorbent polymer per unit area of the second absorbent layers is greater than the content of the absorbent polymer per unit area of the first absorbent layer, and the fibers forming the portions of the second absorbent layers on the side opposite the first absorbent layer have greater durable hydrophilicity, which maintains the hydrophilicity of the fibers, than the fibers forming the portions of the second absorbent layers on the side of the first absorbent layer.