A first proton-donating layer (20a) is a layer having a proton-donative functional group on the surface, for example, a silicon oxide layer. A second proton-donating layer (20b) is also a layer having a proton-donative functional group on the surface, for example, a silicon oxide layer. Negative surface charges are formed on the main surface section of a first base (10a) and the main surface section of a second base (10b), and these negative charges increased the proton conductivity in an aqueous solution fed to a nano channel. Although, in the aqueous solution, proton migration through hopping between water molecules contributes to its diffusion, the negative charges formed on the main surfaces of the bases (10a, 10b) attract protons in the aqueous solution, and the conduction of protons is efficiently achieved in “high-speed transfer regions” formed in the vicinity of the proton-donating layers (20a, 20b).