A native of Osaka, he graduated from Shimizudani High school and Ritsumeikan University, and received a master's degree in sociology of the family from Michigan State University in the United States.
From school days, he continued volunteer activity. After graduation, he served a non-profit organization "ASHINAGA" in Japan, like a "Daddy Long Legs" (traffic-accident orphaned child scholarship association). In 2001, he was elected to the House of Councillors for the first time.
He was the expert of the social welfare, and wrestled with many problems over the social security system such as the reform of a pension policy and the medical system, the foundation of "the nursing care insurance". The question number of times in his Diet was the top-class. There is little legislation introduced by a Diet member in the Japan ("Act of Parliament").
However, he performed much an "Act of Parliament". On May 22, 2006, Yamamoto announced in a speech in the House of Councilors plenary session that he was infected with cancer. He made an effort for the early conclusion of "The Basic Law to Promote Anti-Cancer (Cancer Control Act) ja:がん対策基本法".
On December 22, 2007, Yamamoto died of thymic carcinoma. His seat in the House of Councillors was taken over by Hisako Ōishi on December 28.
Yamamoto was elected to the House of Representatives for the first time in 1993 as a member of Morihiro Hosokawa's Japan New Party but lost the seat in 2000.
Married Keiko Yamakami. 1 child Yho.