Image quality of hardcopy is significantly influenced by paper characteristics. Light scattering phenomena in paper produce optical dot gain, which has a large influence on the tone reproduction characteristics of halftone images. Light scattering phenomena in paper can be represented by the modulation transfer function (MTF) of paper. However, little has been reported on techniques for measuring the MTF of paper. In this study, a new technique for measuring MTF of paper is proposed. We have developed a modified microdensitometer to project a sinusoidal test pattern on sample paper. The reflection density distribution of the projected sinusoidal test pattern was measured by the microdensitometer, and the MTFs of various types of papers obtained. The point spread function (PSF) of paper was calculated by the Fourier transform of the measured MTF. The PSF could be expressed by an exponential function. The obtained PSFs were applied to a model to predict reflection density of the halftone image. This result showed that the predicted density is approximately the same as the measured density in the halftone image and the estimated optical dot gain is well correlated to the measured optical dot gain.