The Shanghai Metro (Chinese: 上海地铁; pinyin: Shànghǎi Dìtiě; Shanghainese: Zaon⁶he⁵ Di⁶thiq⁷) is a rapid transit system in Shanghai, operating urban and suburban transit services to 14 of its 16 municipal districts and to the neighboring township of Huaqiao, in Kunshan, Jiangsu Province.

Forming the vast majority of the broader, multi-operator Shanghai rail transit network, the Shanghai Metro system is the world's second longest metro system by route length, totaling 808 kilometres (502 mi) and the second largest system by number of stations, with 508 stations across 19 lines. It also ranks first in the world by annual ridership, with 3.88 billion rides delivered in 2019. The last daily ridership record was set on 9 March 2024, at 13.39 million rides. Ridership routinely stands at over 10 million on an average workday, accounting for 73% of trips on public transport in the city.

Opening to the public in 1993 with full-scale construction extending back to 1986, the Shanghai Metro is the third-oldest rapid transit system in mainland China, after the Beijing Subway and the Tianjin Metro. Though actual construction and inauguration of the Shanghai Metro succeeded its counterparts in Beijing and Tianjin, their initial planning would date back to the same period, during the late 50s and early 60s, before the impact of the Cultural Revolution.

The system saw its most rapid expansion during the years leading up to the 2010 World Expo, namely, between 2003 and 2010. Between 2007 and 2010, it was customary for new lines and extensions to open on an annual basis. The system is still expanding, with the most recent expansions opening in early 2024, and several new lines and extensions under construction.

The first proposal of a subway system for Shanghai dates back to 1950. Against the backdrop of the air raids of Shanghai by the retreating Nationalist forces in that year, a team of Soviet technical specialists visiting the city made a proposal to the Municipal Committee on Urban Planning and Design for a dual-purpose underground railway system, to be used for mass transit during peace times, and as shelter facility in times of war. It was later, in 1953, during confidential consultations held with Soviet urban planning specialists by Li Gancheng, the then-Deputy Chief and Party Secretary of the Municipal Construction Committee in Shanghai, that the initial concepts of a north-south line and an east-west line were pencilled on a map of the city, which would later become Line 1 and Line 2. Further consultations and public surveys on transit needs were held in 1959 by a Municipal Planning Committee for Underground Railway, in conjunction with the Municipal Public Utilities Management Bureau, and identified multiple alternative plans for a subway system.

In 1960, with a newly-formed a Bureau of Tunnel Engineering, the city undertook an experimental shield tunneling project in Tangqiao, Pudong, excavating a tunnel with a 4.2m-diameter shield for over 100 meters. Dubbed Project 60, this project was carried out in strict confidentiality. In August 1964, the Tunnel Engineering section of the Municipal Urban Construction Bureau completed the route selection phase for the north-south line (later Line 1), which was eventually to connect key locations in the downtown core, including the Shanghai Cultural Square, People's Square and the then Shanghai North railway station, with the rapidly industrializing and urbanizing northern districts of Zhabei and Baoshan, including the industrial zone in Pengpu, the worker's residential area in Zhangmiao, and the town of Wusong. It is ostensibly in this same period that, in 1965, another experimental project on underground tunnel and station construction was underway in a segment between Hengshan Park and Xiangyang Park, both in Xuhui. However, construction halted during the immediately subsequent Cultural Revolution period, and no systematic plan to build an underground railway system materialized.

The economic reforms of 1980s and the rapidly increasing demand for efficient urban public transit saw a swift resurrection of plans for a rapid rail transit system in Shanghai. In 1983, a jointly-published "Proposal on the Construction of a North-South Rapid Rail Transit Line" by the Municipal Planning Committee, the Municipal Construction Committee, in collaboration with the Municipal Bureaus of Urban Planning, of Public Infrastructure, of Railways and of Public Works, called for a rail transit line to be built which connects the city center with Minhang and Jinshan in the south-southwest, and with Wusong and Baoshan in the north-northeast, clearly echoing the initial north-south line concept of the 1950s-60s, though couched in this period in terms of the City's new master plan to "develop both the north and the south wings." Subsequently, in August 1985, a Project Planning Report submitted to the Municipal Planning Committee and the Municipal Committee on Urban and Rural Construction and Management by the Preparation Working Group on the North–South Rapid Rail Transit Line prioritizes the Xinlonghua-to-New railway station segment, and makes a conclusive case for the route of the previously-indeterminate middle segment of the line to be placed under Huaihai Road. Thus, the first stage of the first underground railway line, later Line 1, was determined.

Formal central government-level approval of both the construction of Line 1 and a long-term system-wide plan for the Shanghai Metro came in 1986. In that year, the State Council approved the Master City Plan of Shanghai (1983–2000), the first-ever such approval by the State Council in the history of Shanghai. Part of that Master Plan included a 40-year phased program that would eventually see the construction of 11 metro lines covering over 325 km by 2025. On August 14, 1986, the State Council approved the "Proposal Concerning Construction of Shanghai City Subway Line from Xinlonghua Station to Shanghai Railway Station," clearing the pathway for the beginning of construction of Line 1.