PURPOSE: To enable a sorter to be easily fixed to a copying machine different in conveyance speed, and to enhance versatility, by using a pulse motor for a drive source, and by conveying a copy discharged from a copying machine at a speed adjusted with the frequency of pulses.

CONSTITUTION: A conveyor belt 10 for transporting a copy sheet 4 in a sorter 1 is driven with a pulse motor 13. Therefore, the sorter 1 can be easily mounted on various kinds of copiers 2 even different in conveyance speed due to difference in the copiers 2, only by adjusting pulse frequency to be applied to the motor 13, to a pulse frequency corresponding to its conveyance speed. At that time, terminals for selecting pulse frequency in accordance with the conveyance speeds of various kinds of copiers are provided in a controlling circuit, thus permitting a sorter 1 to be easily fixed to a copier 2 by designating its terminal.