Sędeń Duży [ˈsɛndɛɲ ˈduʐɨ] is a village in the administrative district of Gmina Łąck, within Płock County, Masovian Voivodeship, in east-central Poland. It lies approximately 5 kilometres (3 mi) north-west of Łąck, 11 km (7 mi) south-west of Płock, and 103 km (64 mi) west of Warsaw.