A data sharing method includes detecting by a first data processing apparatus that is among multiple data processing apparatuses that share data, any one among a shortage of available memory, a change in remaining battery power, a change in a relative positional distance of the first data processing apparatus to a second data processing apparatus that is among the data processing apparatuses, a change in a communication speed of communication with the second data processing apparatus, and an interruption of communication with the second data processing apparatus; and transmitting by the first data processing apparatus to a third data processing apparatus that is among the data processing apparatuses, a shared portion of the data saved in the first data processing apparatus.