Janczewice [jant͡ʂɛˈvit͡sɛ] is a village in the administrative district of Gmina Lesznowola, within Piaseczno County, Masovian Voivodeship, in east-central Poland. It lies approximately 3 kilometres (2 mi) north of Lesznowola, 8 km (5 mi) north-west of Piaseczno, and 13 km (8 mi) south of Warsaw.