Disclosed is a method for the purification and collection of a nucleic acid comprising a specific nucleotide sequence, which can be carried out within an extremely short period and can achieve both high sequence-specificity and a high collection rate. Specifically disclosed is a method for the purification of a target nucleic acid comprising a specific nucleotide sequence and contained in a nucleic acid mixture. The method comprises the steps of: hybridizing a photo-ligating nucleic acid having a group represented by formula (I) as abase moiety with the target nucleic acid to form a hybrid; irradiating the hybrid of the photo-ligating nucleic acid and the target nucleic acid with light to cause the photo-ligation of the hybrid; removing any un-photo-ligated nucleic acid by washing; and irradiating the hybrid of the photo-ligating nucleic acid and the target nucleic acid with light to cause the photo-cleavage of the hybrid.