Masuda graduated from the University of Tokyo in 1963, and received his MS degree in 1956 there.
From 1956 to 1977, he worked at Hitachi's Central Research Center and then Systems Laboratory, studying from 1969 at Carnegie Mellon University's Computer Science School on a sabbatical.
His doctorate thesis was on the "Analysis and Evaluation of the Computer System Which Uses Virtual Memory".
From 2003 to 2005, Masuda served as President of the Information Processing Society of Japan.
From 2008, he has served as an Executive Director of the Funai Foundation for Information Technology, which helps those who study abroad to get Ph.D.