To provide users with accurate actual remaining amount information, prevent paper from being run out during use and improve usability, while eliminating unnecessary operation time without preparing dedicated roll paper etc.

This roll paper remaining amount detecting device comprises roll paper rough remaining amount detection for detecting rough amount of remaining roll paper and roll paper detailed remaining amount detection for detecting detailed remaining amount more accurate than the rough remaining amount detected by the roll paper rough remaining amount detection. The roll paper detailed remaining amount detection is made function, only when the amount detected by the roll paper rough remaining amount detection becomes below predetermined amount.