Cyclic Coordinate Method

An adjusting device for adjusting the height of a net pole and the tension of a net rope so as to set up a net used, for example, for a volley ball game, comprises an outer tube, an inner tube telescopically inserted in the outer tube, a stretching means for stretching or releasing a net rope, and a drive means for actuating the inner tube to rise or fall along the outer tube and the stretching means. The drive means is completely housed in the outer tube and actuated by a detachable handle through an opening formed in the outer tube. The rope stretching means is provided at the top end of the inner tube and actuated by the drive means so as to stretch or release the net rope. The drive means is a counter-rotation preventing mechanism per se.