Diaper comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, an absorbent body lying between them, a pair of left and right side sheets forming leak barriers, and an outer sheet, the absorbent body including hydrophilic fibers and a super-absorbent polymer, each side sheet consisting of a front edge region, a center region and a rear edge region, a widthwise outside region of the side sheet being joined with at least one of the top sheet, back sheet and outer sheet, the side sheet being joined with the top sheet at widthwise inside edge sections of the front edge region and the rear edge region of the side sheet, a widthwise inside edge of the center region of the side sheet being a free edge, wherein an elastic member is attached at the free edge and the center region of the side sheet functions as a leak barrier, and the absorbent body consisting of a front region, a crotch region and a back region, there being provided in the absorbent body a pair of left and right fold-inducing bands (8, 8) extending both forward and backward from a center of the crotch region, a distance between the right fold-inducing band and the left fold-inducing band in the widthwise direction being wider at front edges and rear edges of the fold-inducing bands (8, 8) compared to the center of the crotch region, the front edges and rear edges of the fold-inducing bands (8, 8) being located more toward an outer side in a widthwise direction than widthwise inside locations of the joined areas between the side sheets and the top sheet at the widthwise inside edge sections of the front edge regions and rear edge regions of the side sheets, and the fold-inducing bands (8, 8) including hydrophilic fibers and a super-absorbent polymer, but having a lower basis weight and a lower super-absorbent polymer content than the other sections of the absorbent body, wherein a compression groove is formed in each fold-inducing band (8, 8), the compression groove having higher density than the other sections of the absorbent body; wherein the front edges and rear edges of the fold-inducing bands (8, 8) are located on the side edges of the absorbent body, wherein the fold-inducing bands (8, 8) have arc shapes that are convex toward the widthwise center of the absorbent body. the absorbent body including hydrophilic fibers and a super-absorbent polymer, each side sheet consisting of a front edge region, a center region and a rear edge region, a widthwise outside region of the side sheet being joined with at least one of the top sheet, back sheet and outer sheet, the side sheet being joined with the top sheet at widthwise inside edge sections of the front edge region and the rear edge region of the side sheet, a widthwise inside edge of the center region of the side sheet being a free edge, wherein an elastic member is attached at the free edge and the center region of the side sheet functions as a leak barrier, and the absorbent body consisting of a front region, a crotch region and a back region, there being provided in the absorbent body a pair of left and right fold-inducing bands (8, 8) extending both forward and backward from a center of the crotch region, a distance between the right fold-inducing band and the left fold-inducing band in the widthwise direction being wider at front edges and rear edges of the fold-inducing bands (8, 8) compared to the center of the crotch region, the front edges and rear edges of the fold-inducing bands (8, 8) being located more toward an outer side in a widthwise direction than widthwise inside locations of the joined areas between the side sheets and the top sheet at the widthwise inside edge sections of the front edge regions and rear edge regions of the side sheets, and the fold-inducing bands (8, 8) including hydrophilic fibers and a super-absorbent polymer, but having a lower basis weight and a lower super-absorbent polymer content than the other sections of the absorbent body, wherein a compression groove is formed in each fold-inducing band (8, 8), the compression groove having higher density than the other sections of the absorbent body; wherein the front edges and rear edges of the fold-inducing bands (8, 8) are located on the side edges of the absorbent body, wherein the fold-inducing bands (8, 8) have arc shapes that are convex toward the widthwise center of the absorbent body.