Based on the "First Volcanic Eruption Prediction Plan" proposed by the Geodesy Council of the Ministry of Education (currently the Subdivision on Geodesy under the General Committee of the Council for Science and Technology, MEXT), Kakioka Magnetic Observatory began its geomagnetic field observations at Mt. Aso in 1979 as a "volcanic eruption prediction task", which finally ended in October 2022 with the termination of the continuous geomagnetic total intensity observation. This report summarizes the 43-year history of geomagnetic field observations and evaluation of volcanic activities at Mt. Aso Volcano conducted by Kakioka Magnetic Observatory.