Jan Roos, born in Antwerp, was the son of a merchant. He trained as a painter with Jan de Wael, and in 1610 joined the workshop of Frans Snijders, who had recently returned from Italy. In 1614 Roos went to Genoa and then to Rome, where he stayed for nearly two years. In 1616, intending to return to Antwerp, he travelled back via Genoa. His work was in such demand there that he decided not to continue his journey, and stayed in Genoa for the rest of his life.