The 46-year-old required surgery after being gored in the neck, AP reported.
At least two others were taken to hospital for injuries to the head sustained during the annual run, and a total of 48 people were treated by the Red Cross at the scene.
The annual bull running has claimed at least 16 lives since 1910, when records of the deaths first began.
The last person to die was Daniel Jimeno Romero, who died in 2009.
The festival sees daily bull runnings, with participants dressing up in mostly white and red and dashing down the 850 metre course.
Six bulls are released each day, and will be released until Sunday.
The bulls are later showcased during public bullfighting events.
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