A quantity of imparted erasing energy, which is to be imparted to a stimulable phosphor sheet in order to erase residual radiation energy remaining on the stimulable phosphor sheet, is adjusted by use of an image recording sensitivity in a next radiation image recording operation, which is to be performed on the stimulable phosphor sheet, and an energy level of the residual radiation energy remaining on the stimulable phosphor sheet. The quantity of the imparted erasing energy is adjusted such that, as the image recording sensitivity in the next radiation image recording operation, which is to be performed on the stimulable phosphor sheet, becomes high, and as the energy level of the residual radiation energy remaining on the stimulable phosphor sheet becomes high, the quantity of the imparted erasing energy is set to be large.