Marszewnica [marʂɛvˈnit͡sa] is a village in the administrative district of Gmina Lidzbark, within Działdowo County, Warmian-Masurian Voivodeship, in northern Poland. It lies approximately 13 kilometres (8 mi) south-east of Lidzbark, 16 km (10 mi) west of Działdowo, and 76 km (47 mi) south-west of the regional capital Olsztyn.