Fiat-Chrysler Automobiles is controlled by the Agnelli family, whose significant holdings include Juventus, which announced a 112-million euro deal for Ronaldo on Tuesday.
The USB trade union at the Melfi plant said in a statement that it was “unacceptable” to spend so much money while “for years workers have been asked by the company to make huge economic sacrifices.
“Is this fair? Is it normal that one person should earn millions and thousands of families should run out of money mid-way through the month?” USB said.
The union called on FCA to invest more in car production to sustain factory jobs, and called a strike from Sunday at 2000 GMT to Tuesday at 0400 GMT.
The Melfi plant, about 320km southeast of Rome, produces the Fiat 500X and Jeep Renegate SUVs, as well as the Fiat Punto hatchback, which is about to be phased out.