Deflection characteristics of crop (rice, wheat) stalks were examined in order to make clear the mechanical interaction between crops and combine harvester. At the beginning, flexural rigidity values (EI) of crop stalks were calculated from the results of de flection test using image processing apparatus. Further, deflection values and posture of crop stalks were predicted by analysis of Finite Element Method (FEM) using parameters of EI. Therefore, propriety of FEM analysis was examined through the comparison with measured values. Finally, in this study, the following results were obtained: 1) The deflection of crop stalks could be returned to initial condition in a moment against a light load. But, against a heavy load, it took a little time to return to initial condition. Namely, the crop stalks were indicated to have characteristics of viscous elasticity. 2) Deflection values and posture of crop stalks calculated by FEM analysis almost coincided with measured values. From this result, deflection characteristics of crop stalks will be examined theoretically by FEM analysis if EI are obtained accurately. 3) The EI of crop stalks both rice and wheat became larger gradually in the direction of the root according as cross section area of stalk became larger.