The Republic's Cup 1931 was the 31st staging of the Copa del Rey, the Spanish football cup competition. With the proclamation of the Second Spanish Republic on April 14, all teams with "Real" ("Royal") in their names, changed it due to anti-monarchic reasons. Real Sociedad changes to Donostia FC. Most of this changes were done between first and second legs of the first round. The competition started on April 12, 1931, and concluded on June 21, 1931, with the final, held at the Estadio Chamartín in Madrid. Athletic Bilbao won their 11th title, the second in a row.