Poly-vinyl-alcohol (PVA) hydrogel shows unique characteristics, especially self lubrication function and future application is expected such as components in artificial joints. One of the problems for future application is the lack of damage process information on this material. PVA-gel shows strong visco-elasticity and low friction coefficient so that it is difficult to measure volume change and measure mass change directly. Then, this study focus on the damage process itself. Surface damaged by friction was observed and a particulate analysis was performed to obtain basic information on damage process. For this purpose, followings were conducted; discriminated analysis, rectangular bounding, and elliptical shape fitting. Through these treatment, it is suggested that the smaller particle generation is the starter, and there is critical particle size remaining on the bulk surface, and elongation tendency changes during friction.