- 1998 - 1999 : :西ドイツ、ボン、マックスプランク数学研究所研究員
- 1998 - 1999 : :Mit-arbeiter, Max-Planck-Institute of Mathematics, Bonn, West Germany
- 1999 - -: -:茨城大学理学部数理科学科教授
- 1999 - -: -:Professor, Department of Mathematical Sciences, Ibaraki University
- 1991 - 1998 : :東京都立大学理学部数学科助教授
- 1991 - 1998 : :Assistant Professor, Department of Mathematics, Tokyo Metropolitan University
- 1989 - 1991 : :東京都立大学理学部数学科助手
- 1989 - 1991 : :Associate Professor, Department of Mathematics, Tokyo Metropolitan University
- 1987 - 1989 : :西ドイツ、ボン、マックスプランク数学研究所研究員
- 1987 - 1989 : :Mit-arbeiter, Max-Planck-Inctitute of Mathematics, Bonn, West Germany
- 1981 - 1987 : :東京都立大学理学部数学科助手
- 1981 - 1987 : :Associate Professor, Department of Mathematics, Tokyo Metropolitan University
- Ibaraki University College of Science, Department of Science Course of Mathematics and Informatics, College of Science, Department of Science Course of Mathematics and Informatics, College of Science Department of Science (Mathematics and Informatics Cour
