The invention provides an Internet system which can carry out communications among a plurality of clients having terminal computers 1 via intermediate servers while making the locations of transmission sources or receivers secret, wherein specific terminal computers 1 are provided with address converters 2 and transmitting and receiving are carried out by using addresses converted from original addresses that said specific terminal computers 1 have, whereby the Internet system can adapt to various purposes such as to conceal the existence of a transmission source or a receiver, to selectively use a plurality of addresses at a transmission source or receiver side, to use a common converted address at a receiver or transmission source side, to convert information units as necessary, to reject transmission or receiving, etc.