The gain change of the photomultiplier which occurs as the count rate increased was examined. and simple feedback resistor series was introduced between 7th and 9th dynode for compensating the gain change. The effect of the feedback resistor series was considerably good to reduce the gain change. With the feedback resistor, the gain change was only 1.9%, when count rate was increased from 514 CPS (counts per second) to 1250 CPS. Without the feedback resister, the gain change was 6.9%, when the count rate was increased from 530 CPS to 1250 CPS.