An information processing apparatus for executing proxy computing for a person who operates another information processing apparatus connected thereto via a network, by providing its computing resource to the another information processing apparatus, the information processing apparatus comprising: an input unit adapted to receive a permission from a user for executing proxy computing; a communication unit adapted to, when the input unit receives the permission, register its own address in a list stored in a server, an information processor (30, 18d) adapted to execute proxy computing, in a response to selection from the list by an information processing apparatus requesting proxy computing; and wherein the communication unit is adapted to transmit a result of the proxy computing to the information processing apparatus requesting proxy computing, wherein the input unit is adapted further to receive an indication to withdraw the permission from the user, and when the input unit receives the indication while being executing the proxy computing in the information processor (30, 18d), the communication unit informs the information processing apparatus requesting the proxy computing of the indication, and transmits the intermediate data of the proxy computing to another information processing apparatus which is capable of executing proxy computing and newly selected by the information processing apparatus requesting proxy computing, and the information processor (30, 18d) halts the proxy computing, when receiving a switching permission signal, from the information processing apparatus requesting the proxy computing, indicating that the another information processing apparatus becomes capable of continuing to execute the proxy computing, as a result of transmitting the intermediate data by the communication unit. an input unit adapted to receive a permission from a user for executing proxy computing; a communication unit adapted to, when the input unit receives the permission, register its own address in a list stored in a server, an information processor (30, 18d) adapted to execute proxy computing, in a response to selection from the list by an information processing apparatus requesting proxy computing; and wherein the communication unit is adapted to transmit a result of the proxy computing to the information processing apparatus requesting proxy computing, wherein the input unit is adapted further to receive an indication to withdraw the permission from the user, and when the input unit receives the indication while being executing the proxy computing in the information processor (30, 18d), the communication unit informs the information processing apparatus requesting the proxy computing of the indication, and transmits the intermediate data of the proxy computing to another information processing apparatus which is capable of executing proxy computing and newly selected by the information processing apparatus requesting proxy computing, and the information processor (30, 18d) halts the proxy computing, when receiving a switching permission signal, from the information processing apparatus requesting the proxy computing, indicating that the another information processing apparatus becomes capable of continuing to execute the proxy computing, as a result of transmitting the intermediate data by the communication unit.