This paper tries to show the significance of the material the architect Keiji GOTO(1883-1919) left. According to our research, this collection is made up of 7,150 items, whose dates cover almost all of his life. Most of this collection is visual documents. These documents would be the base of his knowledge of architecture. This collection includes the information to show the processes of his designs of his works. And the documents of the structural engineering in this collection include the information on his interest and the sources of his knowledge. And it indicates that he was interested in the ferro-concrete and the statically indeterminate structure and that he studied structural theories and tried to diffuse these new methods. It could trigger a reevaluation of him and could be an example of the introduction of new technology in Japan.