The Diocese of Santa Giusta, formerly Othoca, was a Roman Catholic diocese in Santa Giusta, Sardinia.
The bishop's seat was in the former Santa Giusta Cathedral, now a minor basilica.
The diocese was established in 1119 and abolished in 1503, when it was absorbed into the Archdiocese of Oristano.
Since 1969 Santa Giusta has been a titular bishopric.
This article about a Roman Catholic diocese in Italy is a stub.