Plant seeds are moved in a variety of ways.Wind, insects or animals carries them sometimes.Dispersion by bursting pericarp is a typical movement of plant seeds that is self-active and independent of other creatures.Hereafter, pericarp means wall of fruit, which contains and disperses the seeds.Strain energy is stored in pericarp of fruit due to growth, swelling or drying just before bursting.Thereafter, the storing strain energy is rapidly released when the pericarp bursts.The motion of pericarp during burst depends on their tissue structure and mechanical stress condition just before burst.If a pericarp can burst powerfully and spread seeds widely, it is advantageous in expanding the breeding grounds of a plant.So, the bursting mechanism of a pericarp of existent plants seems to be adapted mechanically and structurally.We clarified that fruit of the Impatiens have outstanding function to disperse seeds far away in previous study [1].The impatience is a kind of autochore plant, that the fruit accumulates stress to burst by swelling, and the pericarps perform roll up motion while bursting.It became clear that pre-burst stress distribution of the pericarp is advantageous to make it large and fast motion for spreading seeds [2].Knowledge obtained in the study is useful to understand the autochore mechanism.In addition to this, there are various kinds of autochore plant that have different bursting mechanism of fruit.We focused on bursting fruit of the Vicia angustifolia in this study.Fruit of the Vicia angustifolia accumulates stress to burst by drying up, and the pericarps scatter seeds by their spiral motion.Laminated structure and fiber tissue arrangement in the pericarp seems very important to consider the bursting mechanism.In this study, the bursting motion was captured by a high-speed video camera.Orthotropic mechanical properties of the pericarp were determined, and the finite-element model considering the Orthotropic was created based on 3D scanning of actual fruit of the Vicia angustifolia.Computer simulation of the pericarp bursting motion by finite-element method was compared to actual motion to validate the finite-element model as shown in Fig.1, and mechanics of the fruit bursting was considered.Furthermore, parametric study changing the fiber direction in the pericarp was carried out to evaluate optimality of the fiber direction for spreading seeds.