A development replenisher replenishment method in an automatic developing machine for a photosensitive lithographic printing plate precursor, the method comprising: developing a plurality of sheets of exposed photosensitive lithographic printing plate precursors with a developer containing an electrolyte while replenishing a development replenisher to keep a developer activity constant, wherein an electric conductivity of the developer is measured every constant period; a development replenisher is replenished every constant time as a time lapse replenisher in an amount based on a set value of a time lapse replenishment rate; a development replenisher is replenished every processing of a constant area of a photosensitive lithographic printing plate precursor(s) as a processing replenisher in an amount based on a set value of a processing replenishment rate; a calculated value of an electric conductivity is calculated from an amount of the time lapse replenisher and an amount of the processing replenisher; and when a set value of a replenishment system indicates an electric conductivity system, the set value of the time lapse replenishment rate and the set value of the processing replenishment rate are increased or decreased according to a result of a comparison of the calculated value of the electric conductivity with the measured value of the electric conductivity of the developer, or when a set value of a replenishment system does not indicate an electric conductivity system, the set value of the time lapse replenishment rate and the set value of the processing replenishment rate are not increased or decreased.