Per Ditlev-Simonsen (born 12 June 1932) is a Norwegian politician.
He was the mayor of Oslo, representing the Conservative Party, from 1995 to 2007.
He stepped down on 23 August 2007 following the Swiss bank-account scandal.
Ditlev-Simonsen was an officer of the Norwegian Royal Guards, and he later attended Stanford University getting a Master of Arts degree.
After college, Ditlev-Simonsen became a partner in his father's shipping company Sverre Ditlev-Simonsen & Co (SDS) in 1955.
He was a partner in the company until 1995.
Ditlev-Simonsen was a Member of Parliament from 1981 to 1985, serving in the Standing Committee of Finance.
From 1989 to 1990 Ditlev-Simonsen was Minister of Defense in the Cabinet of Jan P.