A child asked Francis how he became pope during a visit to a parish in Rome on Sunday.
He said the man picked as pontiff "perhaps isn't the most intelligent, the shrewdest, the quickest to do what has to be done".
But he says the choice "is the one who God wants for that moment for the church".
Francis explained while cardinals discuss the strong points of various candidates, "above all they pray".
The pontiff asked the children who they thought was the most intelligent cardinal in the secret papal conclave at the Sistine Chapel, which ended with his election in 2013.
"You!" they shouted.
But Francis said that was not necessarily the case.
