Provided are a method for strengthening blood vessels with extreme ease and a compression and decompression control system used for performing the method. A compression and decompression control system 1 includes a band adapted to be placed around a particular part of a limb of a user and to apply a compression force to the particular part and a controller for controlling the compression force applied to the particular part with the band. The controller controls the compression force applied with the band in a manner that a compression operation applying a predetermined compression force to the particular part and a decompression operation completely removing the compression force applied to the particular part by the compression operation are alternately repeated. Repetition of the compression operation and the decompression operation allows the vascular endothelial cells of blood vessels of the user to generate a larger amount of nitric oxide, thereby strengthening the blood vessels.