Seongsu Bridge, Cantilever bridge over Han River in Seoul, South Korea

Seongsu Bridge is a cantilever bridge over the Han River linking Seongdong District with Gangnam. Its deck is carried on thick concrete piers with rounded arched openings, three of which stand in the water, and a red steel truss runs beneath the span. Streetlight poles line the top edge, and a dark banner hangs at the far right end.

The original Seongsu Bridge was built by Dong Ah Construction, with work starting in April 1977 and opening on October 15, 1979. On October 21, 1994, a 48-metre span collapsed, killing 32 people. The replacement bridge, built by Hyundai Engineering & Construction, opened on July 3, 1997.

The bridge's name comes from Seongsu-dong, the neighbourhood on its north bank in Seongdong District. The 1994 collapse became a national reference point: it led to emergency inspections of every Han River bridge, the replacement of the Dolsan Iron Bridge, and the 1995 "Disaster Management Act" after the Sampoong Department Store collapse. The 2018 film House of Hummingbird (Beol-sae) depicts the disaster.

The bridge carries four lanes of road traffic between Seongdong and Gangnam, so it is crossed on foot or by vehicle rather than visited as a stop. The 1994 collapse happened during the morning rush hour in rain, when congestion packed vehicles onto the span; crossing outside commuting peaks avoids the heaviest flow.

The 1994 collapse led to emergency inspections of every bridge over the Han River, and the defective Dolsan Iron Bridge was subsequently replaced. The same disaster, together with the 1995 Sampoong Department Store collapse, prompted the creation of the Central 119 Rescue Team, a rescue unit under the National Fire Agency.