A device includes a flow channel through which a solution containing at least one of a target nucleic acid and a nucleic acid recognition body flows. The flow channel includes a flat bottom surface parallel to the flowing direction of the solution and an inclined surface gradually projecting from the bottom surface in the flowing direction. The device also includes a probe electrode provided on the inclined surface. The probe electrode is formed of an exposed portion of a metal film through an opening of a passivation film stacked on the metal film. An angle θ that the probe electrode forms with respect to the bottom surface, a maximal width R of the opening in the flowing direction, and a thickness d of the passivation film satisfy tan θ>d/R.