A method for supporting an idle mode handover of an Single Radio Mobile Station (SR MS) by a target Access Service Network GateWay (ASN_GW) in a heterogeneous wireless communication system is disclosed. The method includes, upon detecting that an operation mode of the SR MS is to be changed from an idle mode to an active mode, acquiring an address of a Home Agent (HA) of the SR MS from a preregistered ASN_GW with which the SR MS has performed a preregistration operation, upon detecting that a Base Station (BS) is to set up a path with the preregistered ASN_GW, transmitting a message, including the address of the HA and requesting to set the target ASN_GW as a new Foreign Agent (FA) of the SR MS, to the preregistered ASN_GW, and upon receiving a message, requesting to register the target ASN_GW as the new FA of the SR MS, from the preregistered ASN_GW, setting up a data path with the HA, and then registering the target ASN_GW as the new FA of the SR MS.