To provide a conveyance device having a simple configuration, conveying even a heavy workpiece smoothly, and improving workability of assembly of parts on a workpiece by making work area a substantially flat surface.

A conveyance path of the conveyance device using an upper part structural body of a construction machine as a workpiece is provided with a slat conveyor 10 and a rail 20, and a conveyance face of the slat conveyor 10 and a rolling face of the rail 20 become substantially the same plane F as a floor face of the work area. Wheels 34 of two carriers 30 roll on the rail 20, and the upper part structural body is provided in workpiece loading parts 33 of each of these carriers 30. A pin insertion hole 35 is provided in a base plate 31, and engaging holes 14 are provided in each slat plate 11 constituting the slat conveyor 10. A connection pin 36 is inserted from an upper part side to tow the carrier 30, and gravity of the upper part structural body 1 is supported on a structural member 21 from the rail 20.