Seibu Dome (西武ドーム, Seibu Dōmu?) is the home field of the Saitama Seibu Lions professional baseball team located in Tokorozawa, Saitama,Japan.

The stadium has a roof over the field and the stands, like other indoor ballparks. However, it lacks a wall behind the stands so that natural air comes into the field. This makes it possible for home runs to leave the stadium, something not possible in typical domed stadiums. The only other covered stadium with a permanent opening is Safeco Field in Seattle, Washington, United States. Its opening is oriented along left and center field, making it possible for home runs to leave that park as well.

The stadium was built in 1979 without the roof and named Seibu Lions Stadium (西武ライオンズ球場, Seibu Raionzu Kyūjō?) as the new home field of the Lions that moved from Fukuoka to Tokorozawa that year. The installation of the roof took place in two phases: the first phase after the 1997 season, and the second phase after the 1998 seasons. At the beginning of the 1998 season, the stadium was renamed Seibu Dome although the domed roof had not completed yet.

On March 1, 2005, the stadium was named Invoice Seibu Dome (インボイス西武ドーム, Inboisu Seibu Dōmu?) as Invoice Inc. bought the naming rights of the stadium for the next two seasons. Upon expiration of the previous contract, on January 1, 2007, the name was changed again to Goodwill Dome (グッドウィルドーム, Guddowiru Dōmu?) to reflect the sponsorship of Goodwill Group, Inc. The naming rights contract with Goodwill was effective for five years. Although Seibu Dome is still the official name of the stadium, the stadium and media use the sponsored name almost exclusively. However, in the end of 2007, as both the stadium and minor team naming right of Goodwill were seized due to Goodwill's illegal business movements, the Dome's name was restored to Seibu Dome in 2008.

The stadium is located in front of Seibukyūjō-mae Station, the terminal station of the Seibu Sayama Line railway (a branch of the Seibu Ikebukuro Line connecting Tokorozawa with Tokyo) and the Seibu Yamaguchi Line people mover. Both lines are operated by Seibu Railway, the owner of the stadium and the Lions.

  • Invoice Seibu Dome (2006)

  • Goodwill Dome (2007)

  • Seibu Lions baseball game (2007)

  • Seibu Dome Artificial turf field (2007)

  • Seibu Dome panorama (2009)