The purpose of this study is to investigate how sensory feedback affects the cognitive strain of grasping using a prosthesis and to develop an efficient method for decreasing the cognitive strain of grasping. We divided a grasping action into two phases, an “approaching phase” and a “grasping phase”, and assumed that the tactile feedback affect for the cognitive strain induced by grasping phase and the deep sensory feedback affect for cognitive strain induced by approaching phase. Using dual-task method, we compared the effect of sensory feedback method using strength-changed simulator or using spatially changed stimulators. As a result, we concluded that the sensory feedback can decrease the cognitive strain of grasping action, and the sensory feedback from one strength-changed stimulator is better than the one from spatially changed stimulators to decrease a cognitive strain caused by grasping action.