The Railway Construction Act (Japanese: 鉄道敷設法, Hepburn: Tetsudō Fusetsu-hō, Law No. 4 of 1892) was promulgated by the Diet of Japan on June 21, 1892, and designated government support for a network of thirty-three railway lines covering most of Japan, with the exception of Hokkaidō. On April 11, 1922, the Diet amended the law to add an additional network of regional and local routes. Today, these lines form the backbone of the national railway network, JR (although JR has relinquished control of some of the more minor ones).

The lines listed below were not covered by the act, since they were already built by that time.

• Tokyo — Gotenba — Nagoya — Gifu — Maibara — Kusatsu — Kyoto — Osaka — Kōbe (Tōkaidō Main Line)
• Tokyo — Hachiōji (Chūō Main Line as Chūō Line Rapid)
• Takasaki — Shinonoi — Nagano — Toyono — Naoetsu (Shin’etsu Main Line)
• Maibara — Tsuruga (Hokuriku Main Line)
• Ōmiya — Takasaki — Maebashi (Takasaki Line)
• Tokyo — Ōmiya — Shirakawa — Fukushima — Iwanuma — Sendai — Kogota — Kitakami — Morioka — Aomori (Tōhoku Main Line)
• Tokyo — Mito (Jōban Line)
• Nagoya — Kameyama — Tsuge — Kusatsu (Kansai Main Line and Kusatsu line)
• Osaka — Ōji — Nara (Tōkaidō Main Line and Nara Line)
• Ōji — Takada
• Kōbe — Himeji — Okayama — Mihara
• Marugame — Tadotsu — Kotohira
• Moji — Kokura — Hakata — Tosu — Kurume — Ōmuta — Kumamoto
• Tosu — Saga
• Wakamatsu — Iizuka

• Railway Nationalization Act
• History of rail transport in Japan