In turbulent mixing of liquid, mixing takes place even in a smaller scale than the Kolomogorov length scale,because of high Schmidt number. In the present study, nearly isotropic turbulence at low Reynolds number was created by a pair of oscillating grid so that the Kolmogorov length can be large. Instantaneous spatial distribution of Rhodamine B concentration under constant mean concentration gradient was obtained by LIF (Laser-Induced Fluorescence) method of which spatial resolution is comparable to the Batchelor length. Noise contained in the measured data is removed by Wavelet decomposition/reconstruction. Some aspect of turbulent mixing within viscous convective range is also observed and further investigation is needed.