The present invention provides a colored sweet potato that has a high anthocyanin content, and that is useful as a pigment material. Further, the present invention also provides a processed product of the colored sweet potato useful as a purple pigment, more specifically, an extract composition, as well as the purified matter thereof (including roughly purified matter).A colored sweet potato having the following characteristics is used.(A) the color value (530 nm) per gram of wet weight of colored sweet potato (color value (530 nm)/g) is not less than 15；(B) the absorbance ratio (320 nm/530 nm) per gram of wet weight of colored sweet potato (absorbance ratio (320 nm/530 nm)/g) is not less than 1.5；(C) color value (530 nm)/g×absorbance ratio (320 nm/530 nm)/g=not less than 30； and(D) LTR retrotransposon (Rtsp-1) is inserted into at least two positions of the genome sequence, and an amplified product having a fragment length of 500 to 530 bp is produced when a nucleic acid amplification reaction is performed using, as a test material, a part of a plant, and at least one of primer set 1 containing a forward primer having the base sequence of SEQ ID NO:1 and a reverse primer having the base sequence of SEQ ID NO:2, and primer set 2 containing a forward primer having the base sequence of SEQ ID NO:1 and a reverse primer having the base sequence of SEQ ID NO:3.
