King Juan Carlos of Spain to Abdicate

King Juan Carlos of Spain, left, and Crown Prince Felipe, his son, attended a military ceremony in January with Queen Sofia in Madrid

MADRID — King Juan Carlos of Spain said Monday that he was abdicating in favor of Crown Prince Felipe, his 46-year-old son, explaining in an address to the nation that it was time for a new generation to “move to the frontline” and take on the country’s challenges.

The king’s abdication, after almost four decades on the throne, follows health problems but also comes amid a decline in his popularity, particularly as a result of a corruption scandal centering on his son-in-law that has also put the spotlight on the royal family’s lifestyle and finances at a time of economic crisis and record joblessness.

Juan Carlos said he resolved to abdicate in January, when he turned 76. He said a generational change would open “a new chapter of hope” for a country hit by a deep economic crisis, while insisting that his son “represents stability,” for Spain as well as for the monarchy.

The king’s son, who will become King Felipe VI, is a former Olympic yachtsman who is regarded as relatively untouched by his family’s scandals. In May 2004, he married Letizia Ortiz, a divorced television journalist. Even before Monday’s announcement, Felipe, who studied international relations at Georgetown University, had increasingly replaced his ailing father on diplomatic trips and at official events.

The king’s abdication was made official earlier on Monday by Prime Minister Mariano Rajoy, who called Juan Carlos a “tireless defender of our interests.” The government is set to meet Tuesday to discuss the legislative change required for the handover to Felipe, which Mr. Rajoy said would happen “very soon.”

Mr. Rajoy also called the abdication “proof of the maturity of our democracy,” a message that was echoed by the leaders of Spain’s other mainstream parties. However, some far-left politicians said Spain should debate whether to maintain its monarchy, with protests convened in Madrid and other cities on Monday evening to call for the abolition of the monarchy. 

Juan Carlos came to the throne in 1975, after the death of Gen. Francisco Franco. He was credited with playing a key role in consolidating Spain’s return to democracy, particularly when he helped avert a military coup in 1981 by making a televised broadcast calling on soldiers to return to their barracks.

 He has also provided a sense of stability in a country confronting separatist efforts in the Basque region and in Catalonia. Such efforts have recently gained momentum in Catalonia, where governing parties want to hold an independence referendum in November that Mr. Rajoy’s government has vowed to prevent because it violates Spain’s Constitution. Juan Carlos has strongly defended Spain’s unity, saying last December, shortly after Catalan politicians unveiled their referendum plan, that the monarchy wanted a Spain in which “we can all fit in.”

The king’s reputation has been tainted by questions about the spending habits of his 48-year-old daughter, Princess Cristina, and her husband, Iñaki Urdangarin, the Duke of Palma, after a judge opened a corruption investigation.

The Spanish royal family’s public standing fell sharply during the period of turmoil after the 2008 financial crisis, which also encouraged Spain’s news media to drop its longstanding deference toward the monarchy and delve into the love life of the king and other previously taboo subjects.

Carmen Enríquez, who has written several books about the royal family and who served as the royal correspondent for Spain’s national television network, said the scandals surrounding the monarchy were unlikely to have persuaded the king to abdicate, but probably added to “the sensation of fatigue” felt by the ageing monarch. She added, “People are demanding a lot more transparency and accountability from the monarchy and all other institutions, and I think the prince is well of aware of this.”

The surprise announcement in Madrid on Monday is not the first sign of change in Europe’s largely ceremonial royal houses in recent years. In April 2013, Willem-Alexander of the House of Orange-Nassau became the first king in the Netherlands in 123 years when his mother, Queen Beatrix, abdicated after 33 years. Later that year, Albert II of Belgium, then 79,signed a declaration of abdication allowing his son, Prince Philippe, to be sworn in as that nation’s seventh monarch since Belgium’s independence in 1830.

In Britain, Queen Elizabeth II, 88, has begun transferring some duties to her son, Prince Charles, 65, but there has been no indication, in public at least, of an abdication in the House of Windsor since Edward VIII relinquished the throne in 1936.

Juan Carlos was born in Rome in 1938, during the Spanish monarchy’s exile and in the midst of a civil war that was followed by a lengthy period of dictatorship under the victorious General Franco. Once in power, Franco brought Juan Carlos back to Spain to oversee his education at a military academy and then handpicked him as the next king. The restoration plan was made formal in 1969 — increasing tensions between Juan Carlos and his exiled father, Juan de Borbón — and the coronation of Juan Carlos took place two days after Franco died in November 1975.

José María de Areilza, a professor of law at the Esade school in Madrid, said that, despite being groomed by Franco, Juan Carlos “was able to understand the change in Spanish society and make himself the engine of that change.” That, he argued, “makes him an extraordinary man in extraordinary circumstances.