PURPOSE: To obtain a plate type cell with small internal resistance and without secular variation by providing one or more spot welding parts in the direction of thickness on the center portion of the plate type cell.

CONSTITUTION: The center portion 21b of a positive polar sheet 21, the center portion 23b of an electrolytic impregnated material 23, the center portion 24b of a conductive plastic film 24 and the center portion 26b of a negative polar sheet 26 are heat-sealed at the same time or prior to heat-sealing of the external circumference of a cell, and center portion of the cell is spot welded in the direction of thickness. Through this spot welding on the center portion of the cell, pushing force is continuously applied in the direction of thickness of the cell and tightness between positive and negative poles is improved, then internal resistance becomes smaller and the secular variation becomes less.