This paper reports an experimental study of the dynamics of s = \pm 1/2 disclinations in the nematic liquid crystalline (LC) phase of 4-cyano-4'-n-pentylbiphenyl (5CB) under strong anchoring condition. The backflow brings asymmetry in annihilation dynamics of disclinations. To reveal the surface effect on backflow, we observed the motion of disclination pair for a various cell gap d. Although the velocity ratio of s = \pm 1/2 disclinations is comparable with a theoretical prediction, it decreased around the cell gap d = 1 μm when velocity ratio was reduced. This observation shows that the backflow is suppressed in the LC cell with d = 1 μm. The anchoring effect is analyzed through a model calculation within an elastic theory.