Raul Castro, 89, made the announcement at the opening of the party’s eighth congress.
He said he was stepping down with the feeling that he had “fulfilled his mission and confidence in the future of our homeland”.
Raul Castro made no mention of who could replace him as the party’s first secretary in a speech on Friday, but he has hinted in advance that he supports the transfer of power to 60-year-old Miguel Dias-Kanel, who took over as president in 2018.