Human error was likely to have been to blame and not a problem with the robot, said VW spokesman Heiko Hillwig late on Wednesday.
The 22-year-old victim was a member of a team setting up the stationary robot. It grabbed and crushed him against a metal plate, Hillwig said.
The man was resuscitated at the factory but died later in hospital, he said.
The Baunatal plant in Germany’s central state of Hesse produces mainly transmissions and electric motors and employs about 15,500 workers.
The contractor worked for a firm from Germany’s eastern state of Saxony.
Charges, but against whom?
Another contractor present was not harmed, Hillwig said.
Such robots normally operate within confined areas at the plant by grabbing auto parts and manipulating them.
The robotic line being assembled had not been formally handed over to Volkswagen, the spokesman added.
The German news agency DPA said prosecutors were considering whether to bring charges, and if so, against whom.
German work and safety rules were recently tightened, requiring risk assessments before the introduction of new equipment.