The prime minister, who backed a Remain vote, said Britain required "fresh leadership" to negotiate the country's exit from the EU.
"I do not think it would be right for me to be the captain that steers our country to its next destination," he said in a statement outside Downing Street.
Close to tears and with his voice breaking, Mr Cameron said: "I love this country and I feel honoured to have served it and I will do everything I can in future to help this great country succeed."
"I do not think it would be right for me to be the captain that steers our country to its next destination," he said in a statement outside Downing Street.
Close to tears and with his voice breaking, Mr Cameron said: "I love this country and I feel honoured to have served it and I will do everything I can in future to help this great country succeed."
Why Britain Joined the European Union