A battery having an electrode unit in which edges of electrode plates are mechanically and electrically connected to a fixing and conducting plate is obtained. A projection is formed at an edge of each electrode plate, and projections are inserted into a grove formed on the fixing and conducting plate. Energy beam is radiated to the fixing and conducting plate along a wall defining the groove, and metal forming the groove is melted and fills a gap between the projection and the groove. The filling metal is solidified at a condition that the melted metal surrounds the projection. The electrode plate is firmly connected to the fixing and conducting plate by a combination of the projection and the surrounding metal. The electrode plates are stably maintained at a positional relationship that the electrode plates extend parallel with each other leaving a gap between adjacent electrode plates, and the electrode plates are connected to the fixing and conducting plate with a reliable electric conductivity.