An electrode plate precursor on which an active material layer is formed by applying an active material onto at least one surface of a current collector in a lengthy belt shape by means of a die comprising a paste storing part where a paste containing the active material is accumulated and a discharge flow path discharging the above paste from the paste storing part. A plan view configuration of the discharge flow path is adjusted by adjusting a plan view configuration of thin plate-like members that are arranged respectively on both end portions of the discharge flow path so that the active material layer formed in the process has a uniform thickness throughout the entire length in the width direction of the electrode plate precursor.