In order to propose the new design method for concrete masonry garden walls and strengthening methods for existing walls with poor seismic resistance, the field investigations of damaged and/or survived masonry walls during the 1995 Hyogoken-nanbu earthquake, damaged masonry walls during the 1997 Kagoshimaken-hokuseibu earthquake and existing garden walls in Oita City were conducted. As the results, the intersecting walls seems to play an important role for preventing significant earthquake damage. Based on the results of field investigation for the existing walls in Oita City, strengthening methods for masonry garden walls with poor seismic resistance are discussed in this paper.