An apparatus is capable of charging a battery mounted aboard a robot while avoiding an unstable posture of the robot caused by a power feeding connector coming into contact to a power receiving connector of the robot. A battery charger of the present invention performs control to move the power feeding connecter to connect with the power receiving connector of the robot in a standing posture, so that a moment generated about a target zero moment point (ZMP) of the robot falls within a range of the moment of floor reaction force generatable about the target ZMP.