Abstract: The directional characteristic of microphone is an important factor in the measurement of directional distribution of sound field. The relations between measured and original distributions are derived. Some components of the directional distribution of sound field can be calculated from the measured distribution. This is especially important, when the directivity of the microphone used is not high. The informations of the directional distribution of sound field which can be obtained from the measurements are limited by the directional characteristic of microphone. Usually, the non-uniformity of the measured directional distribution is less than that of the sound field.