A conservation treatment apparatus for the treatment of an object containing oxide in a conservable state comprising: a placement portion having a conductive placement surface on which the object is placed or a coupling portion having a surface of conductive coupling with which the object is coupled； a conductive enclosure structure configured to continuously conform to an upper portion of the placement portion or configured to be disposed in proximity to the placement portion separately, and surrounding any one of the two sides, front and rear sides and the upper and lower sides of the object, seen from the object placed on the placement surface； one or more electrode assemblies, each electrode assembly being constituted of a DC electrode that contacts any one of the placement portion and the enclosure structure and an AC electrode that contacts the other of the placement portion and the enclosure structure, respectively； a voltage supply portion electrically connected to the respective electrodes constituting the electrode assembly, the voltage supply portion being configured to supply a negative DC voltage to one electrode of each electrode assembly and supply an AC voltage to the other electrode, where one electrode and the other electrode constituting the set of electrodes are disposed respectively in symmetrical positions separately along the extensions of a diagonal line direction in an outwardly expanding plane as seen from the object placed in the positioning portion or coupled with the coupling portion, in a state where at least one of either side, the front and rear sides and the upper side of the object as seen from the object are surrounded by the conductor, the portion voltage supply is applied simultaneously a negative DC voltage and an AC voltage to one and to the other of the electrodes that are disposed separately along both directions along a diagonal line direction where the object is disposed near the center in an outward expansion plane of any
