PURPOSE: To prevent the wear of the battery of a cordless slave machine by deleting a private branch automatic exchange and eliminating the location registration of the cordless slave machine which should be normally performed.

CONSTITUTION: A cordless master machine MQ1 specified of plural cordless master machines MQ1, MQ2 to MQn is provided with a down radio wave transmission sequence storage circuit 19 and a maximum electric field intensity determination circuit 18 determining the cordless master machine receiving the up radio wave of maximum electric field intensity of plural transmission origin cordless master machines radiating down radio wave by a down radio wave transmission sequence storage means. Plural cordless master machines are provided with speech path forming switches SW1 to SW3 forming the speech path of the transmission origin cordless slave machines transmitting up radio wave and the cordless master machines where up radio wave becomes maximum electric field intensity. Plural cordless slave machines are provided with a radio reception circuit 32 receiving down radio wave and a ringer 36 operating in accordance with the calling by the radio reception circuit.