In most cases of the measurement of vibration, by reason of the lightness, the simplicity and the cheapness of accelometer, only accelerationis measured and velocity and displacement are obtained by integrating it. At the time when this integral is put into practice, there is the difficulty that the velocity wave form and the displacement one generally diverge with time because the acceleration wave form contains the direct current component. In the present paper, the basic problems in this integral are discussed and also a few integral techniques avoiding the divergence are described.