Palmira Diaz, 52, found a handbag in the back of a bus while cleaning Tuesday, Think Spain reported.
When she opened the bag, she found a huge quantity of cash inside.
Diaz called over her manager, Sonia Alonso, who in turn called a security guard to accompany them to the National Police station at the bus station.
A police officer counted the money and found 13,900 euros and 2,900 yuans -- totaling more than $18,000.
About an hour later, a Chinese man reported that his wife lost her hand bag while traveling on a bus.
The large amount of cash was apparently for a deposit on a new business they were purchasing in the city.
Diaz, a widowed mother of two daughters, said the money would have "come in very handy," but that her "job and conscience" were "worth more than any amount of cash."