Ohshima Shintaro was born on August 5, 1914, and graduated from Kyushu Imperial University in March 1940. Right after the graduation, Ohshima joined International Electrical Communications, Ltd., and, while developing wireless communication technologies there, he invented, on the contract from Naval Technical Research Laboratory, a novel wireless communication method that could not be intercepted by enemies. It is said that this is something that corresponds today's spreading spectrum communication method.

After the war, Ohshima was appointed an associate professor of the School of Engineering of Nagoya University, and in 1950 joined Electrical Communication Laboratory, where he investigated systematically, under the guidance of Kiyasu Zen-iti, various communication methods, specifically, the optimum communication method based on Shannon's information theory. Then, Ohshima devoted himself in realizing the optimum method with the use of computers. Because computers at the time had many difficulties in speed and reliability to use them for communication purposes, Ohshima became interested in computer technologies.

In 1954, Ohshima joined International Telegraph and Telephone Company (KDD), and, after serving as a Director of the Board and the Director of its Research Laboratory, was appointed Vice-President in 1977. He retired from this position in 1980. While he was with KDD, he had a strong interest in parametron, a unique computer component invented by Goto Eiiti in 1957, and vigorously promoted a joint research work among Takahasi Hidetosi's Laboratory of the University of Tokyo where Goto worked, Electrical Communication Laboratory, and KDD. In addition, in the field of computer technologies, Ohshima developed reliable and high-density plated wire memory element.

On the other hand, because Ohshima had noted the application of digital technologies on communications as promising from its early days, he promoted, in his time with KDD, automatic relaying of telegraph messages by computers, development of electronic switching equipment of telex and telephone messages, etc. These activities made him one of the leaders in promoting International communication technologies. While working for KDD, he served as presidents and directors of various academic societies and contributed the progress of their activities.
Ohshima was conferred the Medal with Purple Ribbon, and the Order of Rising sun, Gold rays with Neck Ribbon.

He died on February 24, 1995.