The award was originally established by Japanese magazine "Nekkyū" in 1947 to honor the career of Eiji Sawamura, a power pitcher who enjoyed an illustrious career for the Tokyo Giants before being killed in combat during World War II. It is a special award that is independent of the official Most Valuable Pitcher award that is presented to one pitcher in each league (Central and Pacific) each year.
The selection criteria were established in 1982; prior to this, a pool of journalists voted on the pitcher they thought was most deserving of the award without any particular criteria. These simply serve as guidelines; while the pitcher who fulfills the most criteria has the most likelihood of winning, pitchers who do not fulfill all seven criteria have often been presented the award.
In the rare event that another pitcher has a season that is deemed more outstanding, a pitcher may, in turn, fulfill all seven criteria and not win the award. In 2008, Hokkaido Nippon Ham Fighters starting pitcher Yu Darvish (16-4, 1.88 ERA, 208 strikeouts) fulfilled all seven criteria, but Tohoku Rakuten Golden Eagles starting pitcher Hisashi Iwakuma won the award despite meeting only six criteria because it was deemed that Iwakuma (21-4, 1.87 ERA, 159 strikeouts) had the better season overall.
Because it began as an independent award by Nekkyū, a magazine catered towards Giants fans, only Central League pitchers were eligible to win the award from 1950 (the first year the NPB employed the current two-league format) to 1989. The first pitcher to be bestowed the honors from the Pacific League was Hideo Nomo for the Kintetsu Buffaloes in 1990.
No pitcher was found to be sufficiently deserving of the award in 1971, 1980, 1984, and 2000. The award has been presented to two pitchers in the same season twice (1966, 2003).
While it is sometimes assumed that the award was introduced following the creation of the Cy Young Award in Major League Baseball, the Cy Young was not introduced until 1956, nine years after the creation of the Sawamura Award.