The fluorescent sand tracers are injected in a point in the surf zone. Core samples are taken from the sixteen points on the circumference with the time intervals of fifteen minutes for about five hours. At the same time, the horizontal two components of fluid velocities are measured at the injection point by using an electromagnetic currentmeter. The field observations have been carried out three times on two beaches facing to the Pacific Ocean. The relations between the local sand movements and the fluid dynamics are examined on the basis of the data obtained.