Railway Technical Research Institute (鉄道総合技術研究所, Tetsudō Sōgō Gijutsu Kenkyūsho), or RTRI (鉄道総研, Tetsudō Sōken), is the technical research company under the Japan Railways group of companies.

RTRI was established in its current form in 1986 just before Japanese National Railways (JNR) was privatised and split into separate JR group companies.

It conducts research on everything related to trains, railways and their operation.

Its research areas include earthquake detection and alarm systems, obstacle detection on level crossings, improving adhesion between train wheels and tracks, reducing energy usage, noise barriers and preventing vibrations.

The RTRI is developing a variable gauge system, called the "Gauge Change Train", to allow 1,435 mm (4 ft 8+1⁄2 in) Shinkansen trains to access 1,067 mm (3 ft 6 in) lines of the original rail network.