Gmina Żarnów is a rural gmina (administrative district) in Opoczno County, Łódź Voivodeship, in central Poland. Its seat is the village of Żarnów, which lies approximately 18 kilometres (11 mi) south-west of Opoczno and 77 km (48 mi) south-east of the regional capital Łódź. The gmina covers an area of 140.7 square kilometres (54.3 sq mi), and as of 2006 its total population is 6,260.