To provide a device easily adjusting pulling means tension of a pulling means transmission device; and its method.

This device 400 adjusting pulling means tension of a pulling means transmission device including at least a first shaft 141, a second shaft 130 and a pulling means belt 150 arranged around both the shafts includes: a body 410 having an accepting part 411 mutually acting with the first shaft, and a mounting-pivoting point 412 mountable so that the body 410 can be rotated around a rotary shaft; and a lever arm 420 extending from the body. The distance D between the first shaft and the second shaft of the pulling means transmission device can be changed by making a load F act on the lever arm 420. This adjustment method of pulling means tension ZK uses torque Fb.