This report provides extracts of various data, including the data obtained from visual inspections as well as the environmental and structural conditions, based on the maintenance plan of the harbor piers along with the existing materials, including the harbor plan map. These data are utilized for conducting statistical analysis and are examined to improve the efficiency of maintenance management in the harbor piers. The analysis reveals that the deterioration tendency of a harbor pier is strongly controlled by the environmental conditions, such as the temperature, humidity, and wind direction, and is strongly associated with the regionality. Further, the deterioration factors are extracted and classified based on the region according to the relation between the environmental and structural conditions of the harbor pier. The observations of this report are expected to support the development of efficient management plans for harbor piers in the future.