The Sapporo Municipal Subway (札幌市営地下鉄, Sapporo Shiei Chikatetsu) is a rapid transit system in Sapporo, Hokkaido, Japan. Operated by the Sapporo City Transportation Bureau, it is the only subway system on the island of Hokkaido, and also the country's only subway system that is entirely rubber-tired.

The system consists of three lines: the green Namboku Line (North–South line), orange Tozai Line (East–West line), and blue Tōhō Line (East-Toyohira line). The first, the Namboku Line, was opened in 1971, prior to the 1972 Winter Olympics. The Sapporo City Subway system operates out of two main hubs: Sapporo Station and Ōdōri Station. Most areas of the city are within a reasonable walking distance or short bus ride from one of the subway stations.

The three lines all connect at Ōdōri Station. The Namboku and Tōhō lines connect with the JR Hokkaido main lines at Sapporo Station, and with the streetcar (tram) above at Ōdōri and Susukino stations. The system has a total length of 48 km (30 mi) with 49 stations. Except for the section of the Namboku Line south of Hiragishi Station, tracks and stations are all underground. The aforementioned above-ground section is entirely covered, including stations, depot access tracks, and the depot south of Jieitai-Mae Station.

In 2024, the system had a daily ridership of 630,000.

All lines of the subway use rubber-tired trains that travel on two flat roll ways, guided by a single central rail. This system is unique among subways in Japan and the rest of the world; while other rubber-tired metro networks, including smaller automated guideway transit lines such as the Port Liner, use guide bars, the Sapporo system does not because the central rail makes them superfluous (similar to some rubber-tyred trams, such as the Translohr and Bombardier Guided Light Transit). This rubber-tired system, combined with the heavy snowfall that Sapporo gets during winter, means that the system must be fully enclosed (including the southern elevated segment of the Namboku line); as a result, rolling stock cannot be fitted with air conditioning as it would otherwise trap hot air in the tunnels. Hence, all trains are equipped with fans and run with windows open to provide ventilation.

There are differences between the technology used on the older Namboku Line and the newer Tōzai and Tōhō Lines. The Namboku Line uses a T-shaped guide rail, double tires, and third rail power collection, while the Tōzai and Tōhō Lines use an I-shaped guide rail, single tires, and overhead line power collection. The surface of the roll ways is constructed of resin (on the entirety of the Namboku Line and the central section of the Tōzai Line) and steel (on the outer sections of the Tōzai Line and the entirety of the Tōhō Line).

5000 series (6-car formation with 4 doors per side, since 1997)

Sapporo Municipal Subway 8000 series (7-car formation with 3 doors per side, since 1998)