We made the long distance communications with different short wave lengths for one year to find out the relation between the wave lengths and possible communication hours, as well as the relation between the wave lengths and the communication distances. In this report is written the general description on the long distance communication on short waves, and the test results for one year, and then the conclusion is given concerning the relation mentioned above. The conclusion arrived at by our experiment is as follows:- (1) The short wave of about 24 meters is critical. (2) Short waves having the wave length of 23 meters or more are best utilized for night long distance communication. (3) Short waves having the wave length of 22 or less are good for daylight long distance communication. (4) It is ascertained that the phenomena of the skipped distance exists in the short wave transmission, especially for the short wave below 20 meters.