A coin identification apparatus comprising: a line sensor that is adapted to detect line image data of a coin being conveyed, the coin being subject to identification; an acquisition unit adapted to acquire the line image data at predetermined sampling intervals to acquire a plurality of line image data, the acquisition unit being further adapted to arrange the plurality of line image data to acquire coin image data, an estimation unit adapted to convert the coin image data to circular coin image data; the estimation unit being adapted to calculate, for each of the plurality of line image data of the converted coin image data, a similarity between the line image data and reference line data for each angle, the reference line data being a part of reference pattern image data indicating a coin having a reference pattern, the estimation unit being adapted to estimate, for each of the plurality of line image data of the converted coin image data, a rotary angle of the coin subject to identification based on the calculated similarity, wherein the reference line data for each angle corresponds to a tangent of a circle concentric with the coin having the reference pattern, and the angle is an angle formed by a reference line passing through the center of the coin having the reference pattern and a perpendicular line from the center of the coin having the reference pattern to the reference line data; a correction unit adapted to correct the plurality of line image data of the converted coin image data based on the estimated rotary angle; and an identification unit adapted to identify the coin subject to identification based on the corrected plurality of line image data. a line sensor that is adapted to detect line image data of a coin being conveyed, the coin being subject to identification; an acquisition unit adapted to acquire the line image data at predetermined sampling intervals to acquire a plurality of line image data, the acquisition unit being further adapted to arrange the plurality of line image data to acquire coin image data, an estimation unit adapted to convert the coin image data to circular coin image data; the estimation unit being adapted to calculate, for each of the plurality of line image data of the converted coin image data, a similarity between the line image data and reference line data for each angle, the reference line data being a part of reference pattern image data indicating a coin having a reference pattern, the estimation unit being adapted to estimate, for each of the plurality of line image data of the converted coin image data, a rotary angle of the coin subject to identification based on the calculated similarity, wherein the reference line data for each angle corresponds to a tangent of a circle concentric with the coin having the reference pattern, and the angle is an angle formed by a reference line passing through the center of the coin having the reference pattern and a perpendicular line from the center of the coin having the reference pattern to the reference line data; a correction unit adapted to correct the plurality of line image data of the converted coin image data based on the estimated rotary angle; and an identification unit adapted to identify the coin subject to identification based on the corrected plurality of line image data.