A method is provided to enable high-density absorption when immobilizing nucleic acid probes onto a solid support surface by suppressing electrostatic repulsion among the nucleic acids. A nucleic acid immobilization method to immobilize a nucleic acid onto a solid support, includes: preparing a solution containing a probe molecule which includes a nucleic acid, a spacer molecule, and at least one kind of a divalent cation; and contacting the solution with the solid support for incubation.