A charging system for a legged mobile robot that facilitates positioning of a robot to be charged and does not put a load on the robot is provided. The charging system includes a battery 2, a power receiving connector 4 and a movable shutter member 5 capable of being opened and closed on a rear cover 3, which are provided on a robot 1, and a holder 21, a power supplying connector 22, a slide mechanism 23, a base plate 25, a charging power supply 26 and the like, which are provided on a charging station 20. The robot 1 performs a predetermined positioning on the base plate 25 and then moves the center of gravity rearward to connect the power receiving connector 4 to the power supplying connector 22. In this step, when the rear cover 3 of the robot 1 is guided by a first guide section 21a of the holder 21, the slide mechanism 23 allows the holder 21 to move horizontally. Thus, even if the robot 1 and the charging station 20 are slightly misaligned with each other, the robot 1 can be easily positioned correctly.