Demonstrators from all over the country marched down Madrid's main avenue, the Gran Via, behind a banner reading "bread, work, homes and equality."
Pan, trabajo y techo demandan miembros de distintos colectivos en la marcha de la dignidad hoy en Madrid. Si se puede. Si podemos. pic.twitter.com/1ity2UXPPi— Hugo Paternina (@Paternina_Hugo) May 27, 2017
Dozens of trade unions and leftwing groups joined the protest.
Organisers put the turnout at 200,000, while the local prefecture put it at only 6,000. An estimate by AFP journalists put it in the tens of thousands.
Labour reforms adopted in 2012 by the conservative government of Mariano Rajoy have helped to spur growth and bring unemployment down from 27 percent at the start of 2013 to 18.7 percent in the first quarter of this year.
But critics say the downside is that many jobs are precarious, with no guarantee of working hours, and are often poorly paid. The minimum wage in Spain is 825 euros per month.