The total number of fatalities in Spain, the third hardest-hit country in the world after the US and Italy, has reached 20,453, the health ministry said.
“It's a number that gives us hope,” said health ministry emergencies coordinator Fernando Simon of the daily death toll, at its lowest in four weeks.
“It's the first time we are under 500 dead since the daily tolls began to climb.”
Health Minister Salvador Illa also said Spain had achieved its objective of “flattening the curve” of transmissions.
But Simon admitted the fall in the number of deaths from Saturday to Sunday can be explained by the lower registration of fatalities over the weekend. Such a drop is often followed by a rise at the start of the week.
Spanish authorities believe the country reached the peak of the pandemic on April 2 when they had counted 950 deaths in 24 hours. But they are not ready to recommend a lifting of the nationwide lockdown, one of the tightest in Europe.
Prime Minister Pedro Sanchez on Saturday announced he would ask parliament to extend the lockdown by two weeks to May 9.
The restrictions currently in place would however be loosened slightly to allow children time outside from April 27, Sanchez said.
Until now only adults have been able to leave the house for specific reasons: to go to work, to go shopping for food or medicine, for a medical appointment or to walk the dog.
But there were growing calls to let children outside, as is permitted in most other countries observing a lockdown.