A computer-readable storage medium having stored therein an information processing program to be executed by a processor of an information processing device capable of acquiring detection coordinates from a pointing device for detecting an input to a predetermined instruction plane, wherein, the pointing device is configured to detect the detection coordinates of a point in one of a plurality of unit areas at which an input was made, the unit areas being arranged in a two-dimensional matrix in the instruction plane, the information processing program causes the processor to function as: an acquisition means (S3, 31) for repeatedly acquiring the detection coordinates detected by the pointing device; the information processing program being characterized in further causing the processor to function as: a detailed coordinate calculation means (S4, 31) being configured to repeatedly calculate, in response to the acquisition of the detection coordinates by the acquisition means (S3, 31), detailed coordinates of a current point (P12, P22) by which a point in the instruction plane can be represented with accuracy in more detail than the detection coordinates, wherein the detection coordinates are represented using integer values and the detailed coordinates are represented using decimal values, and the detailed coordinate calculation means (S4, 31) being further configured to determine a line segment, excluding both ends of said line segment, the line segment connecting a first point with a second point, the first point being a either a previous point indicated by previously calculated detailed coordinates or a previous center point corresponding to the center of the previous unit area, being the unit area indicated by the previously acquired detection coordinates, and the second point being the current center point corresponding to the center of the current unit area being the unit area indicated by the currently acquired detailed coordinates, wherein the detailed coordinate calculation means is further configured to calculate the detailed coordinates indicating said current point (P12, P22) to be the point on the line segment that is within the current unit area and that is closest to the previous unit area. the pointing device is configured to detect the detection coordinates of a point in one of a plurality of unit areas at which an input was made, the unit areas being arranged in a two-dimensional matrix in the instruction plane, the information processing program causes the processor to function as: an acquisition means (S3, 31) for repeatedly acquiring the detection coordinates detected by the pointing device; the information processing program being characterized in further causing the processor to function as: a detailed coordinate calculation means (S4, 31) being configured to repeatedly calculate, in response to the acquisition of the detection coordinates by the acquisition means (S3, 31), detailed coordinates of a current point (P12, P22) by which a point in the instruction plane can be represented with accuracy in more detail than the detection coordinates, wherein the detection coordinates are represented using integer values and the detailed coordinates are represented using decimal values, and the detailed coordinate calculation means (S4, 31) being further configured to determine a line segment, excluding both ends of said line segment, the line segment connecting a first point with a second point, the first point being a either a previous point indicated by previously calculated detailed coordinates or a previous center point corresponding to the center of the previous unit area, being the unit area indicated by the previously acquired detection coordinates, and the second point being the current center point corresponding to the center of the current unit area being the unit area indicated by the currently acquired detailed coordinates, wherein the detailed coordinate calculation means is further configured to calculate the detailed coordinates indicating said current point (P12, P22) to be the point on the line segment that is within the current unit area and that is closest to the previous unit area. a detailed coordinate calculation means (S4, 31) being configured to repeatedly calculate, in response to the acquisition of the detection coordinates by the acquisition means (S3, 31), detailed coordinates of a current point (P12, P22) by which a point in the instruction plane can be represented with accuracy in more detail than the detection coordinates, wherein the detection coordinates are represented using integer values and the detailed coordinates are represented using decimal values, and the detailed coordinate calculation means (S4, 31) being further configured to determine a line segment, excluding both ends of said line segment, the line segment connecting a first point with a second point, the first point being a either a previous point indicated by previously calculated detailed coordinates or a previous center point corresponding to the center of the previous unit area, being the unit area indicated by the previously acquired detection coordinates, and the second point being the current center point corresponding to the center of the current unit area being the unit area indicated by the currently acquired detailed coordinates, wherein the detailed coordinate calculation means is further configured to calculate the detailed coordinates indicating said current point (P12, P22) to be the point on the line segment that is within the current unit area and that is closest to the previous unit area.