A pebble divertor concept is to use the flow of multi layer pebbles as plasma facing component In the divertor plasma, the falling behavior of pebbles is affected by various forces: electromagnetic force, electrostatic force, plasma static pressure and plasma momentum flux. The forces against pebbles in divertor plasma are calculated by referring the edge modeling result of an ITER CDA type divertor. The result of the calculation is that the behavior of pebbles is dominantly affected by the plasma momentum flux. The influence of the electromagnetic force, the electrostatic force and the plasma static pressure can be negligible.