PURPOSE: To enable variously dimensioned cartons to be smoothly reversed by setting a distance between a pair of carton supporting plates so that the lower one of the carton supporting plates is set to the same height as first and second transfer conveyers under the stationary condition of a reversing frame.

CONSTITUTION: A reversing frame 7 is rotated through a chain 10 and a sprocket 8 by a drive motor 9 to reverse upside down a carton transferred by a first cveyer 1, further advance it by a second conveyer 2 and transfer it to the next process with a delivering conveyer 26. During this reversal, the carton is supported from above and below by the carton supporting plates 16 of a pair of arms 14 provided on the reversing frame 7 to carry out smoothly the reversing operation. The distance between a pair of the carton supporting plates 16 is adjusted by the selective change in the engaging position of the arm 14 and the reversing frame 7 such that the lower one of a pair of carton supporting plates 16 is set to the same height as the first and second conveyer 1, 2 under the stationary condition of the reversing frame 7.