In a satellite communication system having a long round-trip delay time, a user terminal reports initial buffer status information when the communication between the satellite and the use terminal started. When a trigger, a timer or padding requiring buffer status information report is generated, the user terminal checks whether there are data to be re-transmitted due to transmission failure from the previous BSR. When transmission-failed data exists, the user terminal sets buffer status amount, which is reported through BSR, as a value that is obtained by adding the amount of transmission-failed data to the amount of newly added after previous report. When there are no transmission-failed data, the user terminal reports BSR which is set as the amount of newly added data to the buffer after previous report. For discriminating entire buffer status reporting and the increased amount of data reporting, the reserved index of a header file is used.