PROBLEM TO BE SOLVED: To provide a stretching/immobilizing device of nucleic acid which does not require modification treatment and a drying process, and is capable of stretching/immobilizing nucleic acid efficiently and with high reproducibility, a stretching/immobilizing method of nucleic acid using the device, a nucleic acid immobilizing member, and a nucleic acid specimen fabricated by the stretching/immobilizing device of nucleic acid.SOLUTION: A stretching/immobilizing device of nucleic acid includes: a nucleic acid immobilizing member including an immobilizing part which immobilizes nucleic acid; an injection port for injecting solution containing nucleic acid; a flow channel of the solution; and a flow channel member including a suction port which sucks the solution. In a stretching/immobilizing method of nucleic acid, nucleic acid is stretched/immobilized to the immobilizing part of the nucleic acid immobilizing member equipped with groove parts which make a pair by sucking solution containing the nu
