To control order of priority in data collection with a single index and to collect data efficiently under a limited electric energy on the basis of the single index.
The portable terminal is provided with a loss detection part 112 for detecting that it is in a loss state and a value information hold part 115 for holding a value evaluation index to be a numerical value showing the value of the data. When the loss state is detected by the loss detection part 112, order of data collection is decided on the basis of the value of the data and the data are transmitted to another terminal. In deciding order of the data collection, the electric energy necessary for data transmission which has been obtained by using an electric energy consumption table 104 and a residual quantity of a battery measured by a battery residual quantity measurement part 108 are taken into account.
KITAGAWA KENJI
MORIMOTO YOSHIAKI
