This method of manufacturing an electrode assembly comprising electrodes that include a tab involves a step for preparing a tab laminate comprising laminated tabs, and a step in which, by irradiating an energy beam onto an end surface of the tab laminate which extends in the direction of lamination of the tab laminate, a welded portion is formed to the inside from the end surface of the tab laminate. In the step for forming the welded portion, when the irradiation direction of the energy beam is projected in the plane that is perpendicular to the end surface of the tab laminate and that includes the lamination direction of the tab laminate, the in-plane direction is inclined with respect to both the lamination direction of the tab laminate and to the direction perpendicular to the direction of lamination of the tab laminate.
