PURPOSE: To provide a cylindrical belt conveyor device by which hanging is not caused in a return side part, needless to say a conveying side part of a cylindrical belt by using a single kind of support panels.

CONSTITUTION: Support panels 11 to support simultaneously a conveying side part and a return side part of a cylindrical belt 12, are arranged at proper intervals in a lengthwise direction of the cylindrical belt 12, and four rollers 13 to support either one of the conveying side part and the return side part of the cylindrical belt 12 from the circumferential direction and two rollers 14 to support either other one of the conveying side part and the return side part of the cylindrical belt 12 from both sides, are provided in the support panels 11, and when a vertical direction of the support panels 11 is changed, needless to say the conveying side part of the cylindrical belt 12, the return side part is also supported in a proper place in the circumferential direction.