Current measurement device and current measurement method using nanopore

A current measuring method, comprising the steps of:

• forming an ion adsorption preventing structure to which a second ion adsorbs to inhibit adsorption of first ions contained in a solution filling a first tank and/or a second tank by wetting a wall surface of a nanopore provided in a thin film with a first solution being a solution containing an ion of a group II element or an acidic solution introduced in at least one of a first tank and a second tank separated by the thin film, the thin film including a material containing Si;
• and
• applying a voltage between a first electrode provided in the first tank and a second electrode provided in the second tank to measure an ion current flowing through the nanopore,
• wherein the nanopore is opened through breakdown of the thin film by applying a voltage between the first electrode and the second electrode, and
• wherein, when the nanopore is opened, at least one of the first tank and the second tank is filled with an acidic solution as the first solution,
• the method further comprising introducing a second solution into the solution tank containing the first solution before measuring the ion current, the second solution having a lower [H+] concentration than the first solution and containing an ion of a group I element,
• wherein the first solution contains potassium ferricyanide or potassium ferrocyanide.