The invention relates to a device for separating metal deposit from a mother plate used as a cathode in an electrolytic process, as metal electrorefining or metal electrowinning, in which device there is a supporting member for supporting the cathode to be treated, a member for releasing at least partly a metal deposit grown during the electrolytic process on a surface of the mother, and a member for support the released metal deposit. According to the invention the mother plate of a cathode (1, 21, 31, 41, 51) is provided with a growth affecting means (16, 24, 36, 43, 53) for creating an irregularity in the growth of the metal deposit (4) to be used as a hinged member when the metal deposit (4) is tilted to the mother plate of the cathode (1, 21, 31, 41, 51) in order to break the metal deposit (4) in two separate pieces along the irregularity in the growth.