A sheet package that is adapted to be set in a printer for supplying to the printer sheets as print media, comprising: a stack of sheets; and a package member covering an exterior of the stack of sheets, wherein: the package member includes a rectangular first portion covering a part of one face of the stack of sheets in a stacking direction, and a rectangular second portion connected with one end thereof to one end of the first portion and covering the one face of the stack of sheets together with the first portion, and the package member further comprises a third portion connected with one of a pair of side ends of the first portion, the pair of side ends being perpendicular to and longer than the one end of the first portion, and that faces the first portion and covers at least a part of the stack of sheets when folded towards the other side opposite to the one side, characterized in that a detection hole or a detection cutout is provided at a position facing the second portion for detecting a presence or an absence of a sheet of the stack of sheets, when the second portion is folded towards one side away from the stack of sheets, a part of the stack of sheets is exposed from the package member and the second portion no longer faces the detection hole or the detection cutout; and the detection hole or the detection cutout is provided in the third portion; wherein the package member completely covers the exterior of the stack of sheets before use, and the detection hole or the detection cutout is formed by removing a part of the package member. a stack of sheets; and a package member covering an exterior of the stack of sheets, wherein: the package member includes a rectangular first portion covering a part of one face of the stack of sheets in a stacking direction, and a rectangular second portion connected with one end thereof to one end of the first portion and covering the one face of the stack of sheets together with the first portion, and the package member further comprises a third portion connected with one of a pair of side ends of the first portion, the pair of side ends being perpendicular to and longer than the one end of the first portion, and that faces the first portion and covers at least a part of the stack of sheets when folded towards the other side opposite to the one side, the package member includes a rectangular first portion covering a part of one face of the stack of sheets in a stacking direction, and a rectangular second portion connected with one end thereof to one end of the first portion and covering the one face of the stack of sheets together with the first portion, and the package member further comprises a third portion connected with one of a pair of side ends of the first portion, the pair of side ends being perpendicular to and longer than the one end of the first portion, and that faces the first portion and covers at least a part of the stack of sheets when folded towards the other side opposite to the one side, characterized in that a detection hole or a detection cutout is provided at a position facing the second portion for detecting a presence or an absence of a sheet of the stack of sheets, when the second portion is folded towards one side away from the stack of sheets, a part of the stack of sheets is exposed from the package member and the second portion no longer faces the detection hole or the detection cutout; and the detection hole or the detection cutout is provided in the third portion; wherein the package member completely covers the exterior of the stack of sheets before use, and the detection hole or the detection cutout is formed by removing a part of the package member.