A foldable pedal apparatus for a vehicle includes pedal assemblies including pedal arms and pedal pads that are rotated rearwards and are thus popped up to a driver so as to be operated by the driver in a manual driving mode in which the driver directly drives a vehicle. Also, the pedal assemblies including the pedal arms and the pedal pads may be rotated forwards and upwards, so as to be located close to a front surface of a footrest panel and thus enter a hidden state in which exposure of the pedal assemblies to the driver is interrupted so as not to be operated by the driver in an autonomous driving situation.