In an assembled battery (10), a plurality of rechargeable unit cells (12), each of which is provided with an electrode body (30) that has a positive electrode (32) and a negative electrode (34), a container (14) that houses the electrode body (30) and an electrolyte, and a positive electrode terminal (15) and a negative electrode terminal (16) which are arranged on an outside of the container (14), the rechargeable unit cells being connected in series. The plurality of unit cells (12) are arranged in a predetermined direction and fastened together while a predetermined load is applied in the arranging direction. Insulating filler (25) is inserted into a gap between the electrode body (30) and an inside wall surface of the container (14) of at least one of the unit cells (12), and a thickness in the arranging direction of each of the unit cells (12) in the fastened state is constant.