A biological signal detection electrode stable in performance over a long period of time includes an insulating base material having electrical insulation, an electrode terminal buried in the insulating base material such that a signal detection surface is included in a part of a lower surface of the insulating base material, a conductive gel film provided on the lower surface of the insulating base material to cover the signal detection surface, an extraction electrode which is connected to the electrode terminal and has a terminal unit exposed on an upper surface of the insulating base material, and a magnetic body to be a counterpart of the conductive magnet disposed below the terminal unit in the insulating base material. The magnetic body is given only the function of mechanical connection, and the electrode terminal is formed of a corrosion-resistant material, for example Ag—AgCl, not corroded by the conductive gel film.