Method of manufacturing storage tank

PURPOSE: A manufacturing method of a storage tank is provided to separately fix plural arc-shaped panels and upper panels without using a separate coupling device by attaching first and second fixing sheets and first and second fitting sheets to the arc-shaped panels and the upper panels. CONSTITUTION: A manufacturing method of a storage tank comprises the following steps: preparing arc-shaped panels (10) and upper panels (20); molding the arc-shaped panels into a shape of a tank body and attaching a first fixing sheet with an area smaller than the area of the arc-shaped panels to the outside of the arc-shaped panels; molding the upper panels into a shape of an upper cover and attaching a second fixing sheet with an area smaller than the area of the upper panels to the outside of the upper panels; and fitting a first fitting sheet between first fixing sheets and a second fitting sheet between second fixing sheets and attaching the fitting sheets to the fixing sheets.