Professor Suganami has published extensively on the following subjects: history of ideas regarding international law and institutions; debates concerning the causes and origins of wars; debates concerning sovereignty in world politics; the history and key contentions of the English School of International Relations; and causation and explanation in the study of world politics. His approach to research is predominantly philosophical (meta-theoretical/meta-historical) and covers philosophical aspects of the study of international relations, especially the application to IR of the philosophy of science/social science/history and the philosophy of law.

Professor Suganami's long-standing interest in the philosophy of law has led to the publication of 'Understanding Sovereignty through Kelsen/Schmitt', Review of International Studies Vol. 33, No. 3, which won BISA's best-article-of-the-year award in 2007. For a number of years, he has also been studying philosophical issues surrounding causation and explanation in science, social science, and history, with a view to clearing the ground where International Relations meets philosophical analysis. With Adam Humphreys, he co-edited a special issue of Journal of International Relations and Development on 'Problems of Causation in World Politics' (2017) and co-authored Causal Inquiry in International Relations (OUP 2024).

Professor Suganami is a graduate of Tokyo University & holds an MSc(Econ) by research in International Politics from the University of Wales, Aberystwyth, & a PhD in International Relations from the University of London. In 1975 he took up a Lectureship in International Relations in the newly established Department of International Relations at Keele University, where, in 1997, he was awarded a personal chair in the Philosophy of International Relations. In 2004 he moved to Aberystwyth University as Professor of International Politics (retired in 2015).  His major publications include: The Domestic Analogy & World Order Proposals (Cambridge University Press, 1989; Japanese edition, 1994); On the Causes of War (Clarendon Press, 1996); & The English School of International Relations (Cambridge University Press, 2004), with Andrew Linklater.  In 2024, he published a major work, Causal Inquiry in International Relations (OUP), with Adam Humphreys of the University of Reading.

Beginning with an early article published in Japanese in the Journal of International Law & Diplomacy (1979) , Professor Suganami has written extensively on the English School of International Relations & some of its central figures (C.A.W. Manning & Hedley Bull in particular); he also contributed to one of the key texts of the English School, Hedley Bull & Adam Watson (eds), The Expansion of International Society (Clarendon Press, 1989; Italian edition, 1994), based on the work of the British Committee on the Theory of International Politics. With Madeline Carr and Adam Humphreys, he has co-edited a collection of essays celebrating the 40th anniversary of the publication of Bull's The Anarchical Society, to which leading scholars from the USA, Canada, Australia, New Zealand, & the UK have contributed (OUP 2017). He is also a co-editor, with Richard Ned Lebow & Peer Schouten, of The Return of the Theorists: Dialogues with Great Thinkers in International Relations (Palgrave, 2016), in which he engages in an imaginary comic dialogue with David Hume as well as Kenneth Waltz (the latter co-authored with Adam Humphreys).