To provide a roll baler device for reaping forage crops with a flail reaping portion 14, transporting the reaped forage crops to a baler chamber 1 via a transport duct portion 2, and then rolling the transported forage crops in the baler chamber, which can solve a problem that the force of transport air from the flail reaping portion is lowered in a half way to make it impossible to efficiently roll the forage crops.

This roll baler device in which the flail reaping portion 14 is disposed at the front end of a machine body to transport reaped forage crops from the flail reaping portion 14 to a baling chamber via a transport duct portion 2 is characterized by disposing a dust-discharging device in the upper portion of the baler chamber 1 or in a transport route.