Santa Giusta (Sardinian: Santa Justa) is a comune (municipality) in the Province of Oristano in the Italian region of Sardinia, located about 90 kilometres (56 miles) northwest of Cagliari and about 3 km (2 mi) southeast of Oristano in the Campidano area. As of 31 December 2004, it had a population of 4,592 and an area of 69.2 square kilometres (26.7 sq mi).