In a time division multiplex access (TDMA-TDD) type wireless communication system in which a communication operation is carried out between a first communication apparatus (mother appliance) and a second communication apparatus (child appliance), and since a slot diversity mode is selected while considering power consumption on the side of the second communication apparatus, the wireless communication system performs such a wireless communication having a higher wireless quality. Based upon a power supply remaining energy capacity on the side of the second communication apparatus, and an electromagnetic wave environment when a wireless signal is received, a slot diversity mode is selected. For example, it is so assumed that 1 frame corresponds to 8 slots, a wireless signal is transmitted from the first communication apparatus to the second communication apparatus by employing two, or more slots, whereas a wireless signal is transmitted from the second communication apparatus to the first communication by employing one slot within the remaining 2 to 6 (8-2) pieces of the slots. As a result, since a total number of the wireless transmission slots used in the second communication apparatus is reduced, transmission electric power can be lowered which may occupy a large ratio within the entire power consumption.