To reveal mechanism of water-repellency of water strider attracts a lot of scientists because of principle of water-repellency can be apply to develop various engineering fields. However, force which had been applied to water-repellent model had estimated value, and principle of water-repellency had not revealed yet. Therefore, we measured the propelling force of the water strider's middle leg directly, and propose a new model which expresses the water-repellency of water strider's legs. When measure water strider's leg force, meniscus between the probe and water surface was prevent the accurate measurement. Thus, we developed a Bio-appropriating probe (BAP) which appropriated water strider's middle leg to sensor prove. By inserting the oaring leg force that we measured directly to new model, we confirmed the consistency of the model.