In this paper, the elastic-plastic displacement shape of the specimen surface during the experiment of compression perpendicular to the grain of the wood was measured using digital image correlation. And, it becomes possible to predict the transition of partial compressive load perpendicular to the grain, by using the stress-strain relation of allover compression perpendicular to the grain. This result is useful in making predictions for the partial compression perpendicular to the grain and the yield strength of wood joints.