PURPOSE: To send an ordinary data at a prescribed rate even if a priority data is generated continuously by splitting the ordinary data into plural segment data and giving the opportunity of transmission to each of priority data and the segment data.

CONSTITUTION: An application program 11 registers a priority data to a data transmission queue means 13 in a data transmitter 1. On the other hand, the application program 12 gives the ordinary data to a segmenting means 14, splits the ordinary data into plural segment data to register one segment data to an ordinary data transmission queue means 15. A transmission control means 16 extracts alternate queue from both of the priority data transmission queue means 13 and the ordinary data transmission queue means 15 and sends the result. Through a series of the operation, the transmission of the ordinary data is implemented for each plural segment data. For example, when the ordinary data is split into n-set of segment data, n-set of priority data are sent while one ordinary data is being sent.