A method and apparatus is disclosed which can reproduce multi-value data with high reproducibility from a hologram recording medium having data recorded in multi-values therein and can reduce the error rate of reproduction data. A reference gradation pattern is recorded in a medium, and luminance unevenness of a gradation pattern obtained by reproducing the gradation pattern is corrected. A gamma characteristic of the medium is determined based on the reproduction gradation pattern, and a modulation pattern produced using easily separable luminance values determined based on the gamma characteristic is displayed on a spatial light modulator to record data in multi-values into the medium. Thereupon, the data are oversampled and recorded, and a block of the reproduced data is decoded depending upon a sequence of relative luminance levels of pixels in the block to decode the entire reproduced multi-value data.