Seosan–Yeongdeok Expressway (Korean: 당진영덕고속도로; Hanja: 唐津盈德高速道路; RR: Dangjin–Yeongdeok Gosokdoro) also known as 6th East–West Expressway is an expressway in South Korea connecting Dangjin to Yeongdeok County.

Numbered 30, it means an East–West expressway.

At 305.5 km, it is the fifth-longest expressway in South Korea.

Two sections of the route, Dangjin-Daejeon Expressway and Cheongju-Yeongdeok Expressway is directly connected with Gyeongbu Expressway.