In a method of manufacturing a capacitor and a method of manufacturing a dynamic random access memory device, an insulating layer covering an upper portion of a conductive layer may be provided with an ozone gas so as to change the property of the upper portion of the insulating layer. The upper portion of the insulating layer may be chemically removed to expose the upper portion of the conductive layer. The exposed upper portion of the conductive layer may be removed so as to transform the conductive layer into a lower electrode. The remaining portion of the insulating layer may be removed, and an upper electrode may be formed on the lower electrode.