Michel Jacques Daniel Piccoli was the son of Henri Piccoli, violinist and Marcelle Expert-Bezançon (1892-1990), pianist and daughter of the French industrialist and politician Charles Expert-Bezançon. In 1954, Michel Piccoli married actress Éléonore Hirt with whom he had a daughter, Anne-Cordélia Piccoli. In 1966, he married the singer Juliette Gréco, then in 1978 the screenwriter Ludivine Clerc, with whom he adopted two children of Polish origin, Inord and Missia.

Placed in an establishment for problem children, the commitments of the young Piccoli, are made in opposition to his maternal grandfather, senator of the Third Republic, financier of the Radical Party, and important industrial painter, accused by the trade union left and by Georges Clemenceau, of having intoxicated his workmen through lead white which causes lead poisoning.