PURPOSE: To manufacture a disk which has a good S/N characteristic and decreases drop-out at a good yield by using warm water and cold water for cleaning with pure water in a developing method in which the photosensitive part of a positive type photoresist film on a glass master disk is dissolved by a developing soln. and is cleaned by the pure water.

CONSTITUTION: The low-concn. developing soln. is discharged for about 10sec from a discharge port 4 by opening a valve 9 while the disk 1 subjected to a photosensitive treatment on a turntable is rotated at 200W300rpm. A valve 10 is opened at the same instant when the valve 9 is closed to discharge the normal developing soln. for prescribed time (about 60sec) from the nozzle 4. A valve 6 is opened at the same instant when the valve 10 is closed to start cleaning with the pure water. The pure water is piped in a heat exchanger 5. The exchanger 5 is so adjusted that the water temp. is 50°C in about 5sec after the discharge of the pure water and attains 15W20°C after 10W30sec. The valve 6 is therefore closed after the cleaning with the warm pure water →the cleaning with the cold pure water is continued for about 2min, then the turntable 2 is rotated at a high speed of 1,000W3,000rpm to drain the water and to dry the master disk.