An object of the present invention is to provide a sending apparatus, sending method and a communication system with utilizing the sending apparatus that can improve efficiency of data sending operation and can reduce a duty for data communication. Each sending apparatus classifies data stored on a storage into groups “X”, “Y” and “Z”, fractionates a clump of data, classified into each of the groups “X”, “Y” and “Z”, by a number of fractions based on a sending completion allowable time for the classified data, and sends the fractionated data in multi cycles at every sending interval, without sending and receiving the data stored on the storage all at once. Each sending apparatus selects any one piece of data generated from fractionated clump of data for each of the groups “X”, “Y” and “Z”, and then sends the selected piece of data at every sending interval.