Provided are a method for a user equipment (UE) to request additional system information in a wireless communication system, and an apparatus supporting the same. The method may include: transmitting a first uplink message including a system information request to a radio access network (RAN); receiving a first downlink message including requested system information from the RAN in response to the system information request; transmitting a second uplink message including an additional system information request to the RAN; and receiving requested additional system information from the RAN in response to the additional system information request.