In a payer-variable exchange system, exchanges 2A and 2B and payer change control devices are provided corresponding to telephones 1A and 1B used by communicators A and B, payer change function units 4A and 4B of the payer change control devices 3A and 3B transmit and receive signals with the payer change function units 4A and 4B of the other parties, a communication amount for which the communicator itself is the payer is calculated by the charge calculation units 5A and 5B, and the same operation is repeated every time a payer change request is received.