To provide a mobile radio terminal that can smoothly transmit data received from a communication terminal.

A transmission available capacity acquisition section 42 extracts reception available capacity information from a signal received from a base station and stores the information to a transmission available capacity storage section 21. A transmission rate information collection section 44 records information of a data transmission rate between the base station and a communication opposite party to a transmission rate information storage section 23. An actual transmission capacity decision section 43 decides an actual transmission capacity for communication between the communication terminal and the base station, in such a way that the average communication speed of the communication will not exceed the data transmission rate, on the basis of the transmission available capacity of the transmission available capacity storage section 21 and the data transmission rate of the transmission speed information storage section 23 and records the decided real transmission capacity to an actual transmission capacity storage section 22. A transmission data flow control section 41 controls communication with the communication terminal through a transmission reception control section 33, on the basis of the real transmission capacity stored in the actual transmission capacity storage section 22 and the capacity of data sent to the base station, so as to avoid the communication terminal to cause time-out.