The present invention provides a sequential and efficient method of assembling a battery with a desired number of layers while reliably separating positive and negative electrode sides from each other with one or more separator structures. According to the invention, the method of assembling a battery includes stacking one or multiple combinations each comprising a frame and a positive electrode plate to be disposed in a region defined by the frame and one or multiple combinations each comprising a frame and a negative electrode plate to be disposed in a region defined by the frame, once or alternately, such that the positive and adjacent negative electrode plates are separated from each other by a separator structure and the periphery of the separator structure is held between the adjacent frames. The separator structure includes a separator exhibiting hydroxide ion conductivity and water impermeability.