A technique is provided which enables simple and low-cost purification of biologically active proteins by means of a conjugate of a target substance capturing molecule and a protein which comprises the amino acid sequence in SEQ ID NO: 1, or a protein which comprises the amino acid sequence obtained by deleting, substituting or adding one or multiple amino acids in the amino acid sequence in SEQ ID NO: 1 and which has binding activity to a compound having -OH or -OR1 [R1 represents a hydrogen atom, an alkyl group or -PO3H2].
