A foldable pedal apparatus for vehicles is provided in which pedal pads are rotated rearwards from a footrest panel and thus enter a pop-up state to be manipulable by a driver in a manual driving mode in which the driver directly drives a vehicle. The pedal pads are rotated forwards maximally close to the front surface of the footrest panel and thus enter a hidden state without exposure to be nonmanipulable by the driver in an autonomous driving situation.