Child, Youth and Family chief executive Paula Tyler has resigned for family reasons and will return to Canada.
Ms Tyler became chief executive in August last year.
Her partner has gone back to Canada to take up the position of chief of staff in the Alberta state premier's office, andMs Tyler has given three months' notice to finish in December.
"In light of my partner's return, I have had to reassess my future options," Ms Tyler said.
"I have very reluctantly decided to resign."
She said her decision to quit was not easy but was made entirely for personal rather than professional reasons.
"I had to choose between a job that is both challenging and hugely rewarding, and being with my partner and family in Canada.
"I have great confidence in the strength and leadership of the current executive committee and I believe the department is in good shape to carry on its good work."
State Services Commissioner Mark Prebble said accepted Ms Tyler's resignation reluctantly.
"During her time [she] has led an extensive refocusing programme for the processes, systems and structure of the department."
Mr Prebble said the State Services Commission will begin searching for a replacement soon.
Child, Youth and Family Minister Ruth Dyson said Ms Tyler had brought valuable management and social development experience to the job, combined with a strong commitment to children, young people and their families.
