An autonomous driving system includes: a Human Machine Interface; and a control device configured to control autonomous driving of a vehicle, present a first operation instruction to a driver of the vehicle during the autonomous driving, the first operation instruction requesting the driver to perform a first response operation performed in response to a first request or a first proposal by presenting the first request or the first proposal to the driver via the Human Machine Interface, and prohibit presenting a second operation instruction different from the first operation instruction until the first response operation is completed or until a timing at which the first response operation is predicted to be completed, the second operation instruction requesting the driver to perform a second response operation performed in response to a second request or a second proposal by presenting the second request or the second proposal.