A simple model of the breakup of a flee in a turbulent flow is proposed by analogy with that of a droplet. In the model, the strength of a flee is expressed as a product of the cohesive force between primary particles and the number of contacts between clusters in the floc. To confirm the validity of this model, three types of polystyrene latex flocs with different fractal dimensions were broken up in the turbulent flow generated with a Rushton type agitator in a mixing vessel. The relation of the maximum diameter of the flee vs the turbulent shear stress was confirmed to obey the scaling law predicted by the proposed model. The power of the relation was also consistent with theoretical prediction.