Remodeling is also an environmentally-friendly approach that reduces the amount of waste in construction site. Specifically, there are many attempts to make house more wide according to the merging of two old houses in apartment buildings. For making two houses into single housing area, openings shoud be needed or walls should be removed. However, removing shearwalls are very dangerous attempt because of reducing of lateral load capacity of buildings. Therefore many engineers prefer to leave shearwalls. However, there are insufficient studies about partial damage, that is, openings. In these cases the damaged shear walls need to be retrofitted by additional materials or members. In this research, four specimens were tested to investigate the capacity of the damaged wall and the retrofitted wall. The artificially damaged wall was prestressed by tendons to improve the shear capacity of the wall, and the other walls were retrofitted by adding steel plate at the surface for the same purpose. Consequently, these retrofitted walls had improved capacity and stiffness in both shear and flexure. Especially, the wall with steel plate showed ductile behavior after ultimate load and the prestressed wall had greater stiffness than the unstrengthened prototype wall.