PURPOSE: To facilitate fitting and detaching a paper-supplying device from a printer, by bringing a contact part provided for a latch lever into contact with a part of a printer or a member affixed to the printer, and turning the lever against an energizing force of an energizing means to engage the lever to a fitting part of a platen.

CONSTITUTION: When mounting the paper-supplying device 1 on the printer 7, an engaging part 8 of a side plate 2 is placed on the upper side of a platen shaft 10, and is lowered as it is. In this case, since the latch lever 4 is energized by a spring 6 in such a direction that an engaging part 11 is not engaged to the platen shaft 10, the engaging part 8 can be smoothly engaged with the shaft 10 without need to operate the lever 4 by fingers or the like. When detaching the device 1 front the printer 7, the contact parts 13 can be sequentially separated from a simply by lifting up the device 1, so that the lever 4 is turned clockwise by the function of the spring 6, and the engaging part 8 can be disengaged from the shaft 10 without trouble.