Gravity separation techniques such as jigging are based on the difference in the settling velocities of particles in water, which depends on the specific gravity, size, and shape of the particles. When a particle falls in stationary water, it is known that its settling velocity in the acceleration period before it reaches its terminal velocity depends on its specific gravity. Therefore, if one jigging cycle were completed before the particle reaches its terminal velocity, separation based on the difference in particle specific gravity would be promoted as the jigging frequency increases. However, there are few reports discussing whether the acceleration period in stationary water could be applied to an unsteady jigging movement. In this study, we used particles of around 1 mm, which are small particles for a jig, and investigated the relation between jigging frequency and particle movement. We have concluded from the results that although the reason is incorrect, the above classical hypothesis reflects the actual phenomenon, since the effect calculated in this study almost agrees with estimations obtained using the hypothesis developed by Gaudin.