Lithium ion assembled battery

Provided is a lithium-ion assembled battery in which two or more single cells are laminated and the DC resistance value between the single cells is low. The assembled battery has two or more single cells including a laminating unit in which a positive electrode current collector, a positive electrode active material layer, a separator, a negative electrode active material layer, and a negative electrode current collector are laminated in order, in the assembled battery, one single cell and the other single cell are laminated such that the positive electrode current collector of the one single cell and the negative electrode current collector of the other single cell are in contact with each other, the positive electrode current collector is made up of a conductive resin layer containing a polyolefin resin (A1) and a conductive carbon filler (B1), the negative electrode current collector is made up of two or more kinds of conductive layers, and the conductive layer disposed on an outer side among the conductive layers in the negative electrode current collector contains the polyolefin resin (A1) and the conductive carbon filler (B1).