A sockliner including a forefoot portion that supports a toe portion and a ball portion of a foot of a user, a midfoot portion that supports an arch portion of the foot of the user, and a rearfoot portion that supports a heel portion of the foot of the user, the sockliner being disposed on an inner bottom surface of footwear for use, the sockliner comprising: a two-layer structure of unitary construction having: a base layer portion disposed with a lower surface facing the inner bottom surface of the footwear; and an upper layer portion having an upper surface and a lower surface, the upper layer portion configured to cover an upper surface of the base layer portion, wherein the upper surface of the upper layer portion is smooth, and wherein the upper surface of the base layer portion and the lower surface of the upper layer portion are boundary surfaces where there is a difference in structure between the base layer portion and the upper layer portion, wherein the base layer portion comprises a three-dimensional mesh structure body (3A, 3B) in which a unit structure is repeatedly arranged in multiple arrays, the unit structure having at least one of a three-dimensional lattice structure and a three-dimensional wall structure, the upper layer portion is formed of a sheet-like structure body comprising a through-hole group including a plurality of holes penetrating through the upper layer portion in a thickness direction of the upper layer portion, each of the holes included in the through-hole group is located inward from a peripheral edge of the upper layer portion without reaching the peripheral edge of the upper layer portion, and in a case where a surrounding region is defined as a region between the peripheral edge of the upper layer portion and a position offset by 4.0 mm inward from the peripheral edge of the upper layer portion, the through-hole group includes an outermost hole group including a plurality of holes located closest to the peripheral edge of the upper layer portion so as to overlap with the surrounding region and to align along the peripheral edge of the upper layer portion. a base layer portion disposed with a lower surface facing the inner bottom surface of the footwear; and an upper layer portion having an upper surface and a lower surface, the upper layer portion configured to cover an upper surface of the base layer portion, wherein the upper surface of the upper layer portion is smooth, and wherein the upper surface of the base layer portion and the lower surface of the upper layer portion are boundary surfaces where there is a difference in structure between the base layer portion and the upper layer portion, wherein the base layer portion comprises a three-dimensional mesh structure body (3A, 3B) in which a unit structure is repeatedly arranged in multiple arrays, the unit structure having at least one of a three-dimensional lattice structure and a three-dimensional wall structure, the upper layer portion is formed of a sheet-like structure body comprising a through-hole group including a plurality of holes penetrating through the upper layer portion in a thickness direction of the upper layer portion, each of the holes included in the through-hole group is located inward from a peripheral edge of the upper layer portion without reaching the peripheral edge of the upper layer portion, and in a case where a surrounding region is defined as a region between the peripheral edge of the upper layer portion and a position offset by 4.0 mm inward from the peripheral edge of the upper layer portion, the through-hole group includes an outermost hole group including a plurality of holes located closest to the peripheral edge of the upper layer portion so as to overlap with the surrounding region and to align along the peripheral edge of the upper layer portion.