Robot with an automatic device for exchanging the batteries of its tool

A robot system, in which various pieces of information are exchanged between a tool (3) on a wrist of a robot and a control panel (4) by wireless communication, includes plural storage cells (1) for supplying the tool (3) with power, plural chargers (2) for charging the plural storage cells (1). An automatic change mechanism (1a) is provided on each of the plural storage cells (1) and transfers an associated storage cell (1) from the tool (3)to one of the chargers (2) and vice versa. When the storage cell (1) being placed on the tool (3) runs out of power, the storage cell (1) is returned to a vacant charger (2) to be charged, while another storage cell (1) which has been charged is received on the tool (3).