Almost 40 years have past since the North American wood frame (two-by-four) construction method became one of the common construction methods for the wooden residential buildings in Japan. The durability of the relatively small cross section size of the framing members, the sheathing materials and the steel connectors such as common nails were in discussion. The object of this research is to evaluate the performance of the shear walls at certain stages of the buildings' service life. The sheathing panels and nails were extracted from wooden existing buildings of certain ages and the extracted sheathing panels and nails were tested for their strength properties. And the strength properties of the aged shear walls were evaluated using a simple structural model and the characteristic values of the aged nail joints.