To clarify very law frequency fluctuations in the torque time series in an agitated vessel, the magnitude and periodicity of the fluctuations were examined from power spectrum analysis and autocorrelation function analysis of the measured torque time series in an agitated vessel with paddle impellers. The fluctuations consisted of quasi-periodic motions with three frequencies, blade passage frequency, rotation frequency, and another frequency (the third frequency), and a nonperiodic and very low frequency motion which was about 290 times long as that of the blade passage frequency. The fluctuation was fractal nature from fractal dimension analysis using the Higuchi method. The correlation dimension of the fluctuation had a non-integer value in the range 3.9-5.2 from correlation dimension analysis using the Grassberger-Procattia method. From these results, it is concluded that the very low frequency fluctuations in the torque time series in an agitated vessel can be described with a deterministic method.