There are many historical brick sluice gates constructed in Saitama Prefecture during the Meiji-Taisho era. This study aims at creating criteria to clarify the characteristics of the sluice gate in Saitama Pref. According to the field and literature survey, they are classified into authenticity, aesthetics, and accessibility to the site and they include surrounding spatial features and situations. These criteria were rated by counting or judging physical and spatial features of the sites. In addition, in order to know the value of the site, the impression of people was observed in a questionnaire survey. It is important to know what criteria contribute the historical impressions of the site for the future conservation and improvement of the site. The impression is quantified into the score of attractiveness, oldness, and historical feeling. The relationship between these scores of impression and scores of physical and spatial features was analyzed. In addition, techniques of conservation and site improvement were classified into nine principles and the method to select appropriate techniques based on the scores of physical and spatial features of each sluice gate.