Director-General of Chief Minister and Treasury Directorate for the ACT has resigned, kicking off a search for the next top public servant to fill the job.

Andrew Cappie-Wood announced his resignation this week, saying he is leaving his post to take up the role of Director General of the New South Wales Department of Attorney-General and Justice in December.

Mr Cappie-Wood was responsible for significant restructuring of the public service during his time in the role, which he began in 2011.

Chief Minister Katy Gallagher said an acting head of the ACT public service will be announced soon, and the recruitment process will begin straight away.