Provided are a method for receiving an on-demand system information (OSI) block by a terminal in a wireless communication system and an apparatus for supporting the same. The method may comprise the steps of: receiving, from a network, an on-demand system information (OSI) configuration including information on mapping between the OSI block and information on a system information request (SIR) preamble; determining an OSI block of interest; selecting an SIR preamble corresponding to the OSI block of interest on the basis of the OSI configuration; transmitting the selected SIR preamble to a serving cell so as to request the determined OSI block of interest; and receiving the requested OSI block of interest.