In Madrid the protesters, many of them wearing green T-shirts that have become a symbol of their movement against the budget cuts, marched to the education ministry where they called on Education Minister Jose Ignacio Wert to resign.
They included groups of students, young parents accompanied by their sign-holding children and teachers.
The protests coincided with a one-day strike by teachers, students and support staff that affected all levels of education.
Organizers claimed a 70-percent turnout by teachers for the strike, while the education ministry put the figure at 20 percent.
"We have a small budget and they are reducing it more and more. There are fewer and fewer teachers and more and more students," said 39-year-old high-school English teacher Fernanda Gonzalez at the Madrid protest.
Protests were also held in several other cities, including Barcelona, Spain's second-largest city, Seville, Valencia, and Zaragoza.
The Platform for the Defence of Public Schools, which groups together students, teachers and administrative staff, called the strike to protest against austerity measures they say are running down the public education system.
They are also angered by a planned education reform, which sets new grading systems, allows for larger class sizes and boosts the proportion of Spanish-language classes at the expense of regional languages.
Prime Minister Mariano Rajoy's conservative government, in power since the end of 2011, has slashed spending to try to reduce a ballooning public deficit.
The education ministry's budget has been cut by 14 percent between 2012 and 2013.
The cuts have caused university tuition fees to soar, led to larger class sizes, fewer grants for graduate studies and cuts to school buses for primary school students in rural areas.