Disclosed is a cordless telephone set capable of suppressing power consumption during power failures to lengthen the time for a call. A cordless telephone (1) receives power supply from a handset (3) placed on a charging section (26) of a base unit (2), during power failures. In order to suppress current consumption of a secondary battery (BT) of the handset (3), the base unit (2) instructs a base unit radio section (21) to be switched to a transmission power-saving mode in which transmission power of the base unit radio section (21) is reduced down to a level at which no communication error occurs, according to radio wave information transmitted from the handset (3) and indicates the received signal strength of a radio signal from the base unit radio section (21) of the base unit (2), received by a handset radio section (39) of the handset (3).