To research in Historical GIS, the first step is constructing the historical administrative boundaries, and then joins them with census data. However, the lack of old maps often makes historical researchers hard to achieve that goals. The maps provided special information at that time only. By contrast, the change of boundaries is successive, especially for basic census area in Taiwan under Japanese rule: Ōaza or Gai/Shō fomerly. This paper indicates that we could construct the historical administrative boundaries with maps form official documents in Taiwan Government-General, which are primary sources and accurate enough. We digitalize and geoprocess those maps in packaged GIS software to construct boundaries, and have ability to present and analysis historical data after joining with them .