A two-dimensional demodulation method for reproducing a data page by means of decision feedback Viterbi detection processing from a recording medium on which a data page has been recorded as a set of a plurality of two-dimensional modulation pattern symbols each of which comprises a plurality of pixels, and which have been modulated two-dimensionally, the method comprising: a step of determining a value of pixel deviation in a reproduction image obtained by receiving light from the recording medium on an image sensor; a step of splitting an output signal of the image sensor which indicates the reproduction image of the light received from the recording medium into signal symbol data by division into blocks in accordance with the two-dimensional modulation pattern symbols; and a step of carrying out decision feedback Viterbi detection for each signal symbol data in accordance with the pixel deviation value.