Disclosed are a method and an apparatus for detecting a defect in a dielectric film. The dielectric film is electrified in an electrolyte solution containing a metal in such a manner the dielectric film is charged negative, thereby the metal is deposited on the dielectric film at a position corresponding to the defect. The detecting method has a first deposition step for forming a first metal deposit on the dielectric film in an annular form surrounding the position corresponding to the defect; and a second deposition step for forming a second metal deposit located on the position corresponding to the defect, on the dielectric film. The detecting apparatus has a vessel for accommodating the electrolyte solution; a first electrode for electrifying the dielectric film and a second electrode; and an electric power source for controlably applying a voltage to electrifying between the first electrode and the second electrode in which a value and a direction of the applied voltage is variable.