Experimental measurement of the local velocity profile around a small bubble in a pressure-oscillating field obtained by the particle tracking velocimetry was performed to study the mechanism of the pressure-oscillating defoaming process. Measurement of the movement of distributed pigments per unit time around the bubble and change in the bubble diameter over a cyclic period of pressure-oscillating enable us to measure the velocity gradient of the fluid directly around the bubble. A high density video camera in Conjunction with strobe lighting was used to record the vibrating bubble, because the applied oscillation frequency was much higher than the frame speed of commercial video cameras. It was found that observed radial velocities were not the same along the bubble surface; radial velocities were high in the lower region of the bubble than the upper region, because the fluid in upper region was surrounded by the rigid cell wall and the fluid was pressed from the downside through a sheet of rubber. Shear rates at the lower and side bubble surfaces, estimated from velocity profile of the distributed pigments, agreed well with previously reported estimates (Iwata et al., 2007), which were derived from deformation of a thin shell liquid around the bubble.