A method and apparatus for supporting mobility in a mobile broadcasting system in which Electronic Service Guide (ESG) discovery is required. The mobility support is classified into three ways according to three different aspects. The first way is to provide roaming information for a local IPDC operator having a roaming partner among local IPDC operators. In the second way, a terminal transmits a query message for requesting transmission of information on a particular local IPDC operator, and receives information on the particular local IPDC operator in response thereto. The third way is to provide the terminal with type information of an ESG; an access type of which is classified according to provision of a roaming service. The roaming information, the information on the particular local IPDC operator and the type information of the ESG, which are provided to the terminal from the mobile broadcasting system, can be provided in an ESG bootstrap level.