Born in Koka, Shiga Prefecture, Iwanaga attended Koka Senior High School and graduated from the law faculty of Chuo University.

After serving as a town council member in Shiga, Iwanaga was elected to the House of Representatives in 1996, representing the fourth district of Shiga.

He became Vice Minister of Agriculture under the first Koizumi cabinet.

[1] On August 11, 2005, Iwanaga became Minister of Agriculture following the resignation of Yoshinobu Shimamura.

This article about a Japanese politician born in the 1940s is a stub.