To reduce the possibility of voice interruption generated by fluctuation in voice communication when the electric field strength of a received radio wave is suddenly changed.

The radio communication terminal device is provided with a radio part 11 for receiving a received radio wave from a base station and outputting a received signal, a reception buffer 20 for buffering a voice data associated with an RTP packet taken out after demodulating the received signal, and a reception buffer adjustment part 25 for instructing a change of the buffer capacity in the reception buffer 20 according to the electric field strength to obtain the electric field strength of the received radio wave. The reception buffer adjustment part 25 instructs to the reception buffer 20 so that the buffer capacity in the reception buffer 20 becomes large as the electric field strength is weaker. Thus, since the reception buffer capacity is determined based on the electric field strength of the received radio wave, a response time up to the change of the reception buffer capacity can be shortened.