The incident occurred during a bull run held in a field in the town of Horche, some 60 kilometres (35 miles) northeast of Madrid.
A bull gored the 82-year-old man in the stomach and thigh, local emergency services officials said.
He was taken by ambulance to a nearby hospital and pronounced dead several hours later.
Local media reported the victim was watching the bull run from a distance.
“I only saw the man when he was already on the ground but it was awful,” Horche mayor Jose Manuel Moral told local media.
The town will go ahead with bull runs scheduled for Tuesday and Wednesday as part of the its annual festival.
Spain is renowned for its bull runs which are held across the country in the summer months when towns hold festivals in honour of patron saints.
A 62-year-old man died on August 29 after being gored in the chest and neck by a bull at a festival in the town of Cuellar in central Spain.
The most famous bull runs take place during the San Fermin festival in the northern city of Pamplona, where hundreds of people come from across the globe to run at their own risk in front of bulls through the city's streets.
Eight people were gored and 35 were injured this year at the Pamplona festival, which was made famous worldwide by Ernest Hemingway's 1926 novel “The Sun Also Rises”.
At least 16 people have been killed in bull runs at San Fermin since records started in 1911, the last fatality was recorded in 2009.