A method for selecting a mobile communication system of a portable terminal comprising: driving a first timer; checking whether a Mobile Country Code,MCC, of a region where the portable terminal is located may be obtained by searching for a network until the first timer expires; when the MCC is obtained before the first timer expires, storing the obtained MCC to a previous MCC list; performing a first checking operation for checking whether the obtained MCC belongs to a list of countries supporting only a Wideband Code Division Multiple Access,WCDMA, mobile communication system; and obtaining a service of the WCDMA mobile communication system by searching for only the WCDMA mobile communication system when the obtained MCC belongs to the list of the countries supporting only the WCDMA mobile communication system; the method further comprising: when the MCC is not obtained until the first timer expires, obtaining an MCC from the previous MCC list; and performing the first checking operation for checking whether the MCC obtained from the previous MCC list belongs to the list of the countries supporting only the WCDMA communication system, and obtaining a service of the WCDMA mobile communication system by searching for only the WCDMA mobile communication system when the obtained MCC belongs to the list of the countries supporting only the WCDMA mobile communication system. driving a first timer; checking whether a Mobile Country Code,MCC, of a region where the portable terminal is located may be obtained by searching for a network until the first timer expires; when the MCC is obtained before the first timer expires, storing the obtained MCC to a previous MCC list; performing a first checking operation for checking whether the obtained MCC belongs to a list of countries supporting only a Wideband Code Division Multiple Access,WCDMA, mobile communication system; and obtaining a service of the WCDMA mobile communication system by searching for only the WCDMA mobile communication system when the obtained MCC belongs to the list of the countries supporting only the WCDMA mobile communication system; the method further comprising: when the MCC is not obtained until the first timer expires, obtaining an MCC from the previous MCC list; and performing the first checking operation for checking whether the MCC obtained from the previous MCC list belongs to the list of the countries supporting only the WCDMA communication system, and obtaining a service of the WCDMA mobile communication system by searching for only the WCDMA mobile communication system when the obtained MCC belongs to the list of the countries supporting only the WCDMA mobile communication system. when the MCC is not obtained until the first timer expires, obtaining an MCC from the previous MCC list; and performing the first checking operation for checking whether the MCC obtained from the previous MCC list belongs to the list of the countries supporting only the WCDMA communication system, and obtaining a service of the WCDMA mobile communication system by searching for only the WCDMA mobile communication system when the obtained MCC belongs to the list of the countries supporting only the WCDMA mobile communication system.