French authorities have discovered the Portuguese truck and its driver missing since the beginning of August.
The man's body was found inside the cab which was parked at a service area 15 kilometres from the French-Spanish border.
The French authorities had been on the look out and were called to a service area where a Portuguese lorry had been parked for some days.
The death of driver José Manuel Gonçalves, 56, was confirmed by the Portuguese Judicial Police, citing information provided by the French authorities.
The driver had started his journey in Norway and was headed to Barcelona. After Montpellier the driver could not be contacted and was last recorded leaving the motorway in the south of France.
After three days of no phone contact, the family of the missing man who was from Braga, contacted police who alerted the French and Spanish authorities.
No foul play is suspected, the police suspect that the man died of a heart attack.
