The membrane of a conventional solid-state nanopore device, which is believed to be promising for understanding the structural characteristics of DNA and determining a nucleotide sequence, has been thick, and the accuracy in determining a nucleotide sequence in the DNA chain has been insufficient. A method characterized by forming a membrane by forming a first film on a first substrate having a surface of Si, then forming a hole in the first film in such a manner that the surface of the first substrate is exposed, then forming a second film on the first film and on the surface of the first substrate and then etching the first substrate with a solution which does not remove the second film.
