Patent ID: 7024996

Claim:
An automatic processing method of a photosensitive lithographic printing plate by developing a plural number of exposed photosensitive lithographic printing plates with a developer, which comprises: previously calculating an electric conductivity value of the developer having an activity falling within a proper range as a target electric conductivity value; measuring an electric conductivity of the developer for every fixed period as previously defined; and replenishing a developer replenisher to the developer in a case where the measured electric conductivity value is lower than the target electric conductivity value, wherein during a period from immediately after start of operation of an automatic processing apparatus until the measured electric conductivity value of the developer exceeds the target electric conductivity value, the target electric conductivity value is corrected using a first operation expression as previously defined for every replenishment of the developer replenisher; and after the measured electric conductivity value of the developer first exceeds the target electric conductivity value after start of operation of the automatic processing apparatus, the target electric conductivity value is corrected using a second operation expression for every replenishment of the developer replenisher.