The 2015 Rakuten Japan Open Tennis Championships was a men's tennis tournament played on outdoor hard courts. It was the 42nd edition of the Japan Open, and part of the 500 Series of the 2015 ATP World Tour. It was held at the Ariake Coliseum in Tokyo, Japan, from October 5–11, 2015.
| Event | W | F | SF | QF | Round of 16 | Round of 32 | width=85 | Q | width=85 | Q2 | width=85 | Q1 |
| Singles[1] | 500 | 300 | 180 | 90 | 45 | 0 | 20 | 10 | 0 | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubles | 0 |
| width=130 bgcolor=dfe2e9 | Event | width=80 bgcolor=lime | W | width=85 bgcolor=thistle | F | width=85 bgcolor=ffff00 | SF | width=85 bgcolor=ffebcd | QF | width=85 bgcolor=afeeee | Round of 16 | width=85 bgcolor=afeeee | Round of 32 | width=85 | Q2 | width=85 | Q1 |
| style=background:#ededed | Singles | $306,200 | $138,000 | $65,400 | $31,555 | $16,100 | $8,850 | $1,000 | $550 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| style=background:#ededed | Doubles | $90,640 | $40,810 | $19,240 | $9,300 | $4,780 |
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| Stan Wawrinka | 4 | 1 | ||
| Kei Nishikori | 6 | 2 | ||
| Gilles Simon | 10 | 3 | ||
| Richard Gasquet | 11 | 4 | ||
| Kevin Anderson | 12 | 5 | ||
| Marin Čilić | 14 | 6 | ||
| Feliciano López | 17 | 7 | ||
| Grigor Dimitrov | 19 | 8 |
The following players received wildcards into the singles main draw:
The following players received entry from the qualifying draw:
Pablo Andújar →replaced by Sam Groth
Gaël Monfils →replaced by Albert Ramos Viñolas
Sam Groth (foot injury) Bernard Tomic (illness)| Country | Player | Country | Player | Rank1 | Seed | |
|---|---|---|---|---|---|---|
| Bob Bryan | Mike Bryan | 2 | 1 | |||
| France | Pierre-Hugues Herbert | France | Nicolas Mahut | 18 | 2 | |
| Raven Klaasen |  Brazil | Marcelo Melo | 30 | 3 | ||
 Austria | Alexander Peya | Brazil | Bruno Soares | 46 | 4 |
The following pairs received wildcards into the doubles main draw:
The following pair received entry from the qualifying draw:
The following pair received entry as lucky losers:
See main article: 2015 Rakuten Japan Open Tennis Championships – Singles.
Benoît Paire, 6–2, 6–4See main article: 2015 Rakuten Japan Open Tennis Championships – Doubles.
Marcelo Melo defeated 
Juan Sebastián Cabal / Robert Farah, 7–6(7–5) , 3–6, [10–7]
