The effects of the location,number and stiffness of guide pads on the lowest critical rotational frequencies of the rotating circular saw damped at the inside and free at the perimeter are discussed by the non linear theory and the perturbation theory of structural vibration analysis The influence of the centrifugal force and the cutting temperature are considered in the course of the analysis The results of the analysis and the calculation show that the introduction of one guide does not stably raise critical rotational frequencies of the circular saw The two guides can raise lowest critical rotational frequency of the circular saw when the angle between the two guides fixed on the direction of the circumference satisfies the certain conditions The effects of the location, number and stiffness of guide pads on the lowest critical rotational frequencies of the rotating circular saw damped at the inside and free at the perimeter are discussed by the non linear theory and the perturbation theory of structural vibration analysis The influence of the centrifugal force and the cutting temperature are considered in the course of the analysis The results of the analysis and the calculation show that the introduction of one guide does not stably raise critical rotational frequencies of the circular saw The two guides can raise the lowest critical rotational frequency of the circular saw when the angle between the two guides fixed on the direction of the circumferential satisfies the certain conditions