After hearing evidence from survivors and bus company staff, the magistrate investigating the accident said there was not enough evidence to prosecute the 62-year-old for homicide through negligence.
According to the magistrate's ruling, there was no mechanical fault and the bus was not speeding.
The driver was not under the influence of drugs or alcohol, took requisite breaks and was not distracted by his mobile phone.
The experienced driver lost control of the coach which crossed the central reservation and crashed into an oncoming car at Freginals, a small town about 150 kilometres (95 miles) south of Barcelona.
Seven Italians and two Germans were among the dead along with another four passengers - from Romania, Austria, France and Uzbekistan - all of them women aged between 19 and 25.