To provide a method for cleansing a glass substrate for a color filter, capable of perfectly eliminating the defects of picture elements after the formation of a black matrix to form stable picture elements in an improved yield by cleansing the glass substrate for the color filter with a strongly alkaline cleansing liquid and subsequently subjecting the cleansed glass substrate to a rinsing and washing treatment.

This method for cleansing a glass substrate for a color filter comprises putting the glass substrate in a strongly alkaline cleansing liquid having a pH of ≥13 at a temperature of ≥30°C, applying an ultrasonic wave cleansing treatment or a brush cleansing treatment to the glass substrate for ≥20sec, and subsequently subjecting the cleansed glass substrate to a rinsing and washing treatment using water heated to ≥30°C at a liquid contact rate of ≥10ml/cm2.