Disclosed are a system and a method for controlling wireless network access information in using a removable external modem. These relates to a case where a removable external modem among devices for a wireless access server (e.g. WiMAX) is connected with a host customer electronics (CE) device so as to be used. Particularly, in a case where the removable external modem, which has no information for accessing a specific network, e.g. operator Lock, a roaming list, a credential, operator ID, etc., when it is introduced, receives network access information through initial access, registration, and provisioning step, and is connected to other device to be used, the modem can be directly connected to a network of an existing registered network communication provider without a separate supplementary registration or a provisioning step.