Wanganui Mayor Annette Main said she received Michael Laws' resignation by email on Sunday afternoon and was pleased it was official, because they could start planning for his replacement.
Mr Laws, whose resignation will come into effect on May 1, is leaving Wanganui for a job in Timaru.
"He has made a decision to move for a position and to move his family. I respect that," said Ms Main.
"I understand that people's circumstances change, and they can change during the time they have been elected to council."
It was "unfortunate" Mr Laws was resigning, but the role of councillor required someone able to be in touch with what was happening in Wanganui.