In order to transmit data via a plurality of types of communication networks in accordance with the communication environment at the time of data transmission, a mobile telephone, which is capable of being connected to a plurality of types of mobile communication networks, is provided with a detector for detecting the communication status of a mobile communication network based on a control signal transmitted from this mobile communication network; a storage unit for storing the detected communication status; an allocation unit for allocating data to each connected mobile communication network based on the amount of the data addressed to another communication apparatus and the stored communication status; and a transmitter for transmitting the data that has been allocated to each mobile communication network to the respective mobile communication networks.