To increase general understandings of fundamental characteristics of microtremors in Hanshin area, microtremors have been observed at Sumiyoshi River-side, Rokko Island, and Nishinomiya. Relations were discussed among the stability of predominant period, successive fluctuation and meteorological conditions. For the analysis, cosine-type taper was conducted before and after 10% of the observed records, and Fourier spectrum was calculated by smoothing using Parzen window with a band width 0.3 Hz. Geometrical mean of two components was used as a horizontal component. At the observation points except Sumiyoshi River-side, predominance in the short period side was not distinct, and was not stable due to the successive fluctuation of predominant period. However, there was less successive fluctuation of spectrum ratio between different two points in the band with period more than 1 sec. Since there was a close correlation between the successive fluctuation in this band and the wind velocity or air pressure, the microtremors in this band was affected by a single vibration source. Ground characteristics could be illustrated by the averages of ratio against base points of moving observation. 14 refs.