Optical recording medium having an indication of a recording capacity, and method for indicating a recording capacity of an optical recording medium facilitates recording or reproducing of an accurate amount of data by indicating the initial recording capacity determined by default and the varied recording capacity by additional allocation of the spare area and the like on particular area of the optical recording medium, and conducting the data writing or reading with reference to the initial recording capacity or the varied recording capacity depending on a state of variation of the recording capacity.