The purpose of this study is to clarify the influence of multiple force, initial development and loading speed to shear strength of structural wooden panels. The following main results obtained by this study are: 1) As the increase of deformation, the influence of multiple force is higher than other case. 2) The influence of initial deformation makes heq larger in micro deformation area, though this isn’t show that the shear walls have enough energy absorption capacity. 3) Loading speed isn’t influence to SIP shear walls.