Instabilities of the slope which mainly consist of solid waste material have occurred in several improper landfills and illegal dumping sites. It is important to investigate the shearing response of solid waste material in consideration of the mechanical stability of dumping site and landfill design. In this study, a direct shear test apparatus that is usable in both in-situ and laboratory was newly developed for solid waste material. The shearing responses of undisturbed waste material were examined by in-situ tests. Furthermore, the influence of structure disturbance, confining stress and initial density to the shearing response and shear strength of reconstituted specimens were investigated by laboratory tests. From the experimental results, it became clear that the density at yield point which depended on initial composition structure and confining stress is key factor for evaluation of shear strength of solid waste material.