Fonterra said a member of its management team, Maury Leyland, had resigned for personal reasons, effective from March 31.
Leyland is the co-operative's managing director of people, culture and safety.
Chief executive Theo Spierings, in a statement, thanked Leyland for her contribution and commitment to Fonterra over the past 11 years.
"During this time Maury has been involved in some defining events for our Co-op," he said.
Leyland worked on the launch of the Fonterra Shareholders' Fund, and with Spierings on the company's "V3" strategy.
She also worked closely on the WPC80 precautionary recall. More recently, Leyland led the response to the 1080 contamination threat.
The process to appoint Leyland's successor is underway.