PURPOSE: To prevent a duplicate feed from occurring after a sheet is supplied by reading, while supplying a sheet, the output signal of a sheet detection means provided between a disposal means and a stack bed and generating an alarm based on its result.

CONSTITUTION: A cover sensor 23 turned on or off in conjuction with a sheet cover 26 freely opened or closed is provided, while a sheet detection means 19 comprised of a light emitting element 29 and a photoelectric element 28 and a stack sheet sensor 22 likewise comprised of a light emitting element 30 and a photoelectric element 28 are provided between a feed-out roller 3 and a handling roll pair 4. When the sheet cover 26 is opened and the cover sensor 23 is turned off while a sheet is supplied, a signal from the sheet detection means 19 is read, and if a sheet is detected, an alarm signal is generated. Thus, a duplicate feed can be prevented from occurring after a sheet is supplied.