The invention relates to a method for producing a mother plate used in electrolytic cleaning and to the mother plate which plate comprises a metal plate (1), a plate support member (2) and a plastic edge strip (6) provided on at least one of the sides (3,4,5) of the metal plate (1). According to the invention, in order to form the edge strip (6), in the mother plate (1) there is attached a mold (7) provided with an extruder (11) for extruding the edge strip material (12), so that the extruder (11) is made to proceed, with respect to the mold (7), essentially along the whole length of the mold (7), and that prior to detaching the mold (7) from the mother plate (1), the edge strip material (12), such as ethylenic acid copolymer, is rendered in an essentially solid form. Moreover, according to the invention at least two opposite sides (3,4) of the mother plate (1) are provided with an edge strip (6).