The principal of Christchurch Girls' High School has announced she is resigning after recently resuming the role following a controversial reinstatement.
The school's board of trustees terminated Prue Taylor from her position in November last year over what it said was bullying behaviour by her and a breakdown in her relationship with the board.
Mrs Taylor took the case to the Employment Relations Authority and was granted interim reinstatement.
She says she had been considering retirement for more than a year, and with the upcoming board of trustee election it was a good time to step down.
Mrs Taylor says staff were stunned when she told them that she was ending her 40-year teaching career.
She will leave at the end of the second school term.