He was born in Kristiania as a son of postmaster Erik Emanuel Erichsen (1884–1963) and Petra Antoine Olsen (1885–1930).
[1] In 1951 the idea of appointing Erichsen as a State Secretary in the Ministry of Finance was discussed, but it did not happen.
[1] Following a stint as a director in the Organisation for European Economic Co-operation from 1956 to 1957, he returned to Norway to serve as permanent under-secretary of State of the Ministry of Finance from 1957 to 1986.
[6] He edged out the other applicants, Einar Grøstad and Sigurd Lorentzen, partly due to him being an economist and the other two being jurists.
A festschrift was issued on his seventieth birthday, and in 1999 Erichsen released the retrospective Glimt fra et langt liv i Finansdepartementet.