"In 'modernising' our national museum, the restructure has disestablished the positions of all five natural history collections managers who are specialists in their field, to be replaced by two assistant curators, two generalist collection managers, and a technician."
Martin said today that he had achieved "what he set out to do" at the Wellington museum and that Te Papa was in a strong position.
"It has been a privilege to be part of the team leading Te Papa, it is a truly special place, and my time at the museum will always be a highlight of my career," Martin said.
"It really is an honour to work with the taonga of the nation, and with the incredible team here who live and breathe that every day."
Te Papa Board chairwoman Dame Fran Wilde said Martin "took up his role at a time when Te Papa faced a number of issues, including the need to upgrade vital infrastructure and an organisational structure that required some re-shaping".
"He took up these challenges, and this focus on the organisational and physical infrastructure has given us a strong platform to develop our public offering for the future," Wilde said.
Martin will remain chief executive until the end of the year while recruiting is underway for a replacement.