Disclosed is an electric storage device to be used in a power receiving apparatus in a wireless power transmission system. The electric storage device (13) is provided with a plurality of electric storage cells (36) connected in series. Each of the electric storage cells (36) is provided with: an electric storage element (37) which stores charges; a container (38) which houses the electric storage element; a power receiving antenna (30), which can receive power transmitted from the power transmitting antenna (22) of a power feeding apparatus (24) in the wireless power transmission system; and a charging control circuit (31) which charges the electric storage element (37) using power received by means of the power receiving antenna (30). All of the electric storage cells (36) can be charged to the right level by wirelessly charging the electric storage cells (36) at the same time.