An information processing system comprising: an acquisition means configured to acquire vibration of a device that vibrates during operation, as time-series data of a physical quantity indicated by three-axis components in a three-dimensional coordinate system; a calculation means configured to calculate a first evaluation value indicating a degree of bias of the vibration of the device between axes, based on the time-series data of the physical quantity; and an estimation means configured to estimate a degradation level of the device based on the first evaluation value, wherein: the calculation means is configured to: calculate a first index indicating a degree of variation of the time-series data of the physical quantity for each axis component using all of the three-axis components of the time-series data of the physical quantity; convert each axis component of the first index by a predetermined conversion process, to calculate a second index; calculate a product of axis components of the second index, as the first evaluation value; and calculate, based on a plurality of pieces of time-series data of the physical quantity detected in a respective plurality of periods that are different from each other, a plurality of first evaluation values corresponding to the respective plurality of periods, and the estimation means is configured to: calculate a second evaluation value indicating a degree of variation of the plurality of first evaluation values, and estimate the degradation level based on the second evaluation value; and set the second evaluation value or a common logarithm of the second evaluation value as the degradation level. an acquisition means configured to acquire vibration of a device that vibrates during operation, as time-series data of a physical quantity indicated by three-axis components in a three-dimensional coordinate system; a calculation means configured to calculate a first evaluation value indicating a degree of bias of the vibration of the device between axes, based on the time-series data of the physical quantity; and an estimation means configured to estimate a degradation level of the device based on the first evaluation value, wherein: the calculation means is configured to: calculate a first index indicating a degree of variation of the time-series data of the physical quantity for each axis component using all of the three-axis components of the time-series data of the physical quantity; convert each axis component of the first index by a predetermined conversion process, to calculate a second index; calculate a product of axis components of the second index, as the first evaluation value; and calculate, based on a plurality of pieces of time-series data of the physical quantity detected in a respective plurality of periods that are different from each other, a plurality of first evaluation values corresponding to the respective plurality of periods, and the estimation means is configured to: calculate a second evaluation value indicating a degree of variation of the plurality of first evaluation values, and estimate the degradation level based on the second evaluation value; and set the second evaluation value or a common logarithm of the second evaluation value as the degradation level. the calculation means is configured to: calculate a first index indicating a degree of variation of the time-series data of the physical quantity for each axis component using all of the three-axis components of the time-series data of the physical quantity; convert each axis component of the first index by a predetermined conversion process, to calculate a second index; calculate a product of axis components of the second index, as the first evaluation value; and calculate, based on a plurality of pieces of time-series data of the physical quantity detected in a respective plurality of periods that are different from each other, a plurality of first evaluation values corresponding to the respective plurality of periods, and calculate a first index indicating a degree of variation of the time-series data of the physical quantity for each axis component using all of the three-axis components of the time-series data of the physical quantity; convert each axis component of the first index by a predetermined conversion process, to calculate a second index; calculate a product of axis components of the second index, as the first evaluation value; and calculate, based on a plurality of pieces of time-series data of the physical quantity detected in a respective plurality of periods that are different from each other, a plurality of first evaluation values corresponding to the respective plurality of periods, and the estimation means is configured to: calculate a second evaluation value indicating a degree of variation of the plurality of first evaluation values, and estimate the degradation level based on the second evaluation value; and set the second evaluation value or a common logarithm of the second evaluation value as the degradation level. calculate a second evaluation value indicating a degree of variation of the plurality of first evaluation values, and estimate the degradation level based on the second evaluation value; and set the second evaluation value or a common logarithm of the second evaluation value as the degradation level.