To provide a device for smooth join without giving a shock to a free tray, when the free tray is joined from the conveyers running in two lines to a one line conveyer.

Carrying-in conveyer mechanisms 1 provided in two lines, and a joining conveyer 310 to join the free trays 2 carried in from the two lines of carrying-in mechanisms 1 alternately into one line by closing their widths, are provided, the two lines of carrying-in conveyer mechanisms 1 have main carrying-in conveyers 101, and conveyers 103 for speed regulation to form the conveying route final parts, and they connect phase difference detecting devices 5 and 7, a deciding means to detect the adequacy of the phase difference of the running in two lines at their joining time, depending on the detected phase difference data, and a conveyer speed variable control means 6 to variably control the carrying speed of the conveyer 103 for speed regulation depending on the deciding result of the detecting means.