An object of the invention is to obtain a biotinylated nucleic acid efficiently, by enhancing dissociation efficiency of biotin in the biotinylated nucleic acid and tamavidin 2 in a tamavidin 2-immobilized insoluble carrier. The inventive method for separating a biotinylated nucleic acid includes (1) contacting a sample containing a biotinylated nucleic acid wherein the biotin is bound to the nucleic acid with a insoluble carrier on which tamavidin is immobilized (a tamavidin-immobilized insoluble carrier) to form a complex of the biotinylated nucleic acid and the tamavidin-immobilized insoluble carrier, and (2) separating the biotinylated nucleic acid from the complex in a solution having pH of 7.8 to 9.5 and in the presence of free biotin. The invention also provides a method for separating the biotinylated nucleic acid to which the nucleic acid-binding protein is bound, a method for separating the nucleic acid-binding protein, and a kit for separating the nucleic acid.