The 2009 Rakuten Japan Open Tennis Championships is a tennis tournament played on outdoor hard courts. It is the 37th edition of the event known that year as the Rakuten Japan Open Tennis Championships, and is part of the 500 Series of the 2009 ATP World Tour. It is held at the Ariake Coliseum in Tokyo, Japan, from October 5 through October 11, 2009.
The Rakuten Japan Open Tennis Championships is the longest-running ATP World Tour tennis tournament in Asia, first held in 1973. A combined ATP World Tour and Sony Ericsson WTA Tour event, it is played at Ariake Colosseum, which is an enormous tennis centre consisting of 48 tennis courts and a stadium with one of the first retractable roofs in tennis.