A dual band portable phone includes a first mobile phone system used in a first mode, a second mobile phone system used in a second mode, a storing section and a control section. The storing section has a mode area for storing a mode data indicative of a current operation mode, a first area for storing a first control channel data indicative of a first control channel used for the first mobile phone system in the first mode, and a second area for storing a second control channel data indicative of a second control channel used for the second mobile phone system in the second mode. The mode data indicates the first mode at present. The control section performs a position registration of the portable phone using the second control channel data stored in the storing section to set the second mode, when a first radio communication using the first mobile phone system becomes impossible while the first radio communication is performed in the first mode. The control section also performs a second radio communication using the second mobile phone system.