The principle of the measurement method and an interpretation of the Dember signal of photographic emulsion microcrystals are described. The current signal under short-circulted condition (low load resistance) reflects the difference between the sum of the velocities of diffusing electrons and that of diffusing holes, while the potential difference signal under open-circuited condition (high load resistance) reflects the degree of separation between electrons and holes. Comparison of these two Dember signal waveforms with the signal waveform of microwave photoconductivity seems useful for clarifying the behavior of holes in emulsion microcrystals.