PURPOSE: To improve handling capacity ever so better, by making the length of an expansion chute adjustable in accord with the height of a powdery granular body, in case of a chute expansion device to be used when the powdery granular conveying work transferred by a belt conveyor is made to drop down in succession.

CONSTITUTION: This expansion chute that is attached to a boom tip of a continuous conveying machine consists of a fixed chute 2 locked to a turning frame 1 to be installed in the underside of the boom tip and plural expansion chutes 3W5 being fitted in the lower part of a chute 2 in series in a telescopic way, and the expansion chute is expanded or contracted by rotation of a hoisting drum 6 via wires 7 and 8. In addition, a spoon 10 is pivotally attached to the lower end of an expansion chute 5 at the lowest stage, and a control lever 12 is displaced in a longitudinal direction by an electric motor 11 whereby the spoon 10 is turned round. Furthermore, a way sprinkling device 13 is attached to the lower end of the chute 5, through which sprinkling takes place against powdery granular bodies dropped down to an accumulation repositoty 14, thus dust is prevented from scattering.