The history of starch sweetener was initiated in 1811 by Kirchhoff's discovery to have obtained sweet syrup and sugar from potato and wheat. Also the finding of glucose isomerization in alkaline solution by C. A. Lobry de Bruyn and W. A. Ekenstein has been considered as the important discovery in the basic and applied carbohydrate chemistry. Glucose isomerase was first discovered by Marshall and Kooi has led to the innovation in the starch sugar industry after the extensive researches to search for the effective and stable enzyme with high activity. By the combination with the technology of the immobilized enzyme, the continuous isomerization has been industrially achieved. Some aspects of the history and chemistry of the glucose isomerization are described in this paper. Also the present situation and future potential of utilization of the isomerized syrup are discussed.