1968-1973 Research Institute for Mathematical Sciences, Kyoto University, Research Assistant 1973-1974 College of Liberal Arts, Kagoshima University, Lecturer 1974-1986 College of Liberal Arts, Kagoshima University, Associate Professor
1986-1997 College of Liberal Arts, Kagoshima University, Professor 1997-2009 Faculty of Science, Kagoshima University, Professor
2009 Professor Emeritus at Kagoshima University
1994-1995 Center for Advanced Study at the Norwegian Academy, Visiting Researcher
2009-2014 Part-time Lecturer at Education Center of Kagoshima University (Mathematics)
2011-2013 Part-time Lecturer at Faculty of Science of Kagoshima University (Department of Mathematics and Computer Science)
2012-2014 Part-time Lecturer at Faculty of Education of Kagoshima University (Department of Mathematics)
