PURPOSE: To smoothly transport waste straw, to reduce operation amount in a handling part and to miniaturize the handling part in the case of selectively sending threshed waste straw to plural different waste straw treating parts in a waste straw changing device for carrying out the selection.

CONSTITUTION: A rail 11 for guiding waste straw is arranged in a waste straw transporting part 4 and a selecting guide 12 is connected movably in the shaft direction to the rear end of the rail. A driving means 14 for moving the selecting guide 12 consists of a reciprocating moving pulley 18 and a rope hung on the moving pulley 18. In this case, a changing plate 9 of a waste straw treating part 3 is linked to the driving means 14 by a handling means 13 and driven. The selecting guide 12 is slid by operating the handling means 13 and transportation of waste straw to the plural treating parts 3 is selected by varying the projected amount of the selecting guide 12.