PURPOSE: To automatically maintain a desired tensile force without suspending a drum or a weight, by providing a slackness and tension adjusting unit shifting the shaft of a driven where toward a conveyor stretching direction and controlling its driving unit by the operation of a slackness and tension detecting means.

CONSTITUTION: In a rope conveyor in which a rope 3 is wound between a driving wheel 1 and a driven wheel 2, a slackness and tension detecting unit 15 is gradually shifted by the spring force of a compression coiled spring 25 toward a direction to stretch the rope 3 according to the extension of the rope 3. When the extension is generated, an emergency slackness detecting segment 20 is shifted to a position to detect a segment 23 to be detected. When a detection signal is outputted from the detecting segment 20, a driving motor 28 is driven to shift an actuation rod 22 of the slackness and tension adjusting unit 21 toward a rope stretching direction. Thereby, the detecting segment 23 is shifted to the left side against the force of a spring 25, in oder to operate a normal tension detecting segment 19. By a detection signal of the detecting segment 19, rotation of the driving motor 28 is stopped, and the tension of the rope 3 is set in a desired stretching condition.