PURPOSE: To enable a belt conveyor device to be adjusted in a widthwise direction, simplified in mechanism and made compact, including easy belt drive control.

CONSTITUTION: This conveyor device is equipped with a stationary carrier guide 12 having carrier pulleys 10a and 10b, and a movable carrier guide 16 having carrier pulleys 14a and 14b, and laid in as a way as in parallel with the guide 12 and freely adjustable in distance therefrom. An outer supporting point pulley 18 is fitted outside the guide 16 and an inner supporting point pulley 20 is fitted in the vicinity of the guide 12. Also, the first and second driven pulleys 22a and 22b moving together with the guide 16 are arranged. In addition, a common belt 24 is extended between each pulley. In this case, a belt section between both stationary and movable guides 12 and 16 is made to have an S-form and the belt 24 is driven by a motor 24.