Dr. Martin J.T. Milton, Director of Bureau International des Poids et Mesures (BIPM), visited Japan on 22nd-26th January 2018 for promotion of redefinition of SI base units and lectured on “The future of the International System of Units (SI)” in Kyoto and Tokyo. On 22nd January, he visited Industrial Science and Technology Policy and Environment Bureau of METI, and had fruitful discussions on the research activities of NMIJ and BIPM. In Kyoto, on 23rd January, as an invited speaker of Kyoto AIST Measurement and Analysis Fair, he spoke to the participants from measurement-analytical manufacturers in the Kansai area. He also talked with AIST President, Dr. Ryoji Chubachi in Kyoto as a courtesy call. On 24th January, he moved to Tokyo, and attended the 13th International Metrology Symposium as an invited speaker too. The symposium was held by the Japan Metrology Forum and NMIJ aiming to impart the benefits provided by redefinition of SI base units. The audience included the press and educational publishers too. In both of his lectures, the overview of the redefinition based on fundamental constant was introduced and the impact of the redefinitions was described. On the final day, on 25th January, he visited NMIJ in Tsukuba and discussed with NMIJ fellow researchers about the future of the SI Units.