Abstract: A health care system comprises plural subscriber terminal devices, a data management center, and a communication line connecting the subscriber terminal devices to the data management center, wherein each subscriber terminal device comprises an input means for inputting health data of the corresponding subscriber, a storage means for holding the inputted health data, a first communication means for performing data communication with the data management center, a display means for displaying the health data and information from the data management center, and an operation means with which the subscriber performs a series of operations; and the data management center comprises a second communication means for performing data communication with each subscriber terminal device, a storage means for holding health data transmitted from each subscriber terminal device, a group decision means for deciding a group to which each subscriber belongs on the basis of plural pieces of health data obtained from the storage m