Measurements have been made for the effective thermal diffusivity of dispersed materials which consist of different thermophysical properties. The measurement results are obtained by the periodical heating method, and are compared with the predicted value calculated from effective thermal conductivity, effective specific heat and effective density. The equation to predict the effective thermal diffusivity may be applicable in the range in which the volume fraction of dispersed particles is less than 0.25. It may be recognized also that the effect of particle shape is exerted with increasing thermal diffusivity ratio of particle to matrix.