Thousands of demonstrators including health, transport and administrative workers marched in central Madrid and Barcelona, to the din of horns, drums and yells of "Government resign!"
Similar demos were called in 60 cities in a nationwide movement led by the two main trade unions, CCOO and UGT, and a wide collective of other civil groups.
They were the latest in months of strikes and protests against Prime Minister Mariano Rajoy's austere economic reforms in a recession that has driven the unemployment rate over 26 percent.
Sunday's actions were called "against unemployment and for the renewal of democracy," the UGT said in a statement.
Protestors raged against Rajoy's spending cuts, which they say are hitting public services such as schools and hospitals and sharpening hardship in the recession.
"Bread and a roof at a fair price," read some of the signs waved by protestors. Others brandished pictures of Rajoy with the words "Wanted: serial con man".
Rajoy says the cuts are necessary to meet the targets for cutting Spain's budget deficit that he has agreed with European authorities. He insists the painful measures will strengthen Spain's finances and economy in the long run.
Protestors complained that through this austere economic drive the government and European Union leaders were imposing unfair suffering on citizens.
They also vented anger at the political establishment, aggravated by recent investigations into alleged corruption in the governing Popular Party and even the royal family.
"Our current problems can only be solved by political change," said one demonstrator in Madrid, Pilar Gomez, a 52-year-old nursing assistant, wrapped in a red, yellow and purple Republican flag.
"The risk premium is going down and the stock market is going up. But the one thing that isn't changing is the six million people unemployed," she said.
"We can't allow them to condemn us to economic misery with the stroke of a pen."
The UGT in its statement urged "a radical and urgent change in economic policy in Europe as well as Spain".
"The policies of 2012 have been a resounding failure in tackling the crisis and have only made all our problems worse," it said.
The Spanish unions held Sunday's demonstrations ahead of a European Union-wide protest called by the European Trade Union Confederation on March 13th and 14th.