A portable communication terminal comprising of the present invention includes a first wireless communication unit 102 corresponding to a first wireless communication system, an interface 107 to which an external apparatus 200 can be removably connected, a determination unit 111 for determining whether the external apparatus 200 connected to the interface 107 includes a second wireless communication unit 202 corresponding to a second wireless communication system, a battery voltage detection unit 104 for detecting a battery voltage of a power supply unit 103 including a battery, and a control unit 111 for controlling the external apparatus 200 based on whether a communication by the first wireless communication unit 102 is present, a determination result of the determination unit 111, and the battery voltage detected in the battery voltage detection unit 104. Thereby, an influence on the main communication system due to the addition of the sub-communication system is reduced, so that a multi mode communication depending on the battery voltage can be efficiently carried out without any unpredictable situation for a user to occur.