Born in Toyama Prefecture. After working in the human resource development department of a general corporation, Nitta has been a full-time employee of the Japan NPO Center since 1998, Secretary General of the same organization since 2004, concurrently Director of the Civil Society Network on SDGs since 2007, and Director and Secretary General of the same organization since 2009. Nitta currently serves as co-secretary of the G7 Civil Society Coalition 2023 and is a part-time lecturer at the Faculty of Human Environment, Hosei University.