Abstract: The characteristics of the non-zonal current in the barotropic nondivergent atmosphere and its bound condition are discussed. A suggestion that some period oscillation of non-zonal current in the low latitudes should be the oscillation generated upon β-effect is put forward. Further, expression of the disturbance wave velocity in non-zonal current is obtained by use of the barotropic vorticity equation on the β-plant. Finally, an example which approximately confirmed the expression is given.