Purpose: The pressure sore is a trouble by the mechanical loading. As for this, the stress concentration occurs to the skin surface, and, next, sphacelation is meant by the skin. However, there is a case where the pressure sore is not improved even if the stress is removed. For this case, defective fixation of the skin is more remarkable than the general person. In this research, the appraisal method was quantitatively proposed for the soundness of the skin. Design/methodology/approach: This paper proposed the model of the mechanism where the skin received the shear stress and the pressure sore was generated. To verify this model experimenting, it examined it in pathology. Findings: The experimental results showed that first of all, to measure the viscoelastic property of the skin with in vivo, the measuring instrument using the rheometer was developed. Next, it made comparative study with the state of pathology of the pressure sore with this measuring instrument. As a result, it was able to be suggested that defective fixation of the skin decide the form of the pressure sore. In addition, it has understood though the state of the therapeutic approach and the prognosis can be evaluated. Research limitations/implications: In this research, the skin was measured using the probe and the rheometer which devised the stage. At this time, the datum point of the rheometer measured by assuming in the bone upper part. Practical implications: This paper cleared that it is influence of the measurement place of a skin viscoelasticity value. As a result, it was suggested that the preventive care of the bedsore becomes possible. Originality/value: The objective of this research project was to develop the skin appraisal method was quantitatively proposed.