Oranga Tamariki is struggling to recruit several hundred more social workers as it faces new demands to protect and help vulnerable children.
The outgoing chief social worker, Paul Nixon, told Nine to Noon the government agency was also under pressure to find caregivers for children.
Under Oranga Tamariki - Ministry for Children, 6350 children and young people are in state care, with the agency employing 1300 social workers.
Oranga Tamariki was established last year in a shake-up designed to ensure frontline social workers were given the capacity to spend more time with families and vulnerable children and more targeted support to children deemed at risk.
In 2014 a qualitative review of Child, Youth and Family (CYF) social worker caseload, casework and workload management found 50 percent of social workers' time was spent on administrative tasks and only 25 percent with children.
In 2015 the Children's Commissioner's annual report questioned whether children were better off in state care.
Mr Nixon said there had been slow improvements since 2014, with social worker-to-child ratios going down from 31 to 26.
"Ideally it should be 15 children per social worker and 10-to-12 children for new social workers, " he said.
One of the key priorities of the organisation was recruiting new staff, which had proven difficult.
The government's agreement with social workers on a pay equity settlement worth $114 million over five years yesterday would help in that respect, he said.
"The pay deal will help make the job more sustainable and more attractive."
About 700-to-800 new social workers were needed to take up care and protection roles. There was also a 12 percent turnover of existing staff each year.
Fifty percent of children in care were Māori, while 26 percent of social workers were also Māori.
Oranga Tamariki faced more demands next year, including providing care for 18-to-21-year-olds, as young people stayed in care for longer.
Mr Nixon said was also a serious shortage of mental health workers and clinical psychologists.
"As we become more aware of the complex needs of children and the impact of trauma we do need more support from clinical psychologists and mental health nurses to help both caregivers and children in recovery," he said.
Having control of purchase and commissioning powers helped direct resources towards mental health needs, such as addressing self-harm and the threat of suicide.
He said a practical package to support caregivers had been established, but there were still not enough caregiver social workers to meet demand.
"We are constantly under pressure each day to find a day caregiver for a child and that is a real stress at site level and can consume all our energy and time trying to find a caregiver on that day for that child," he said.
"We are putting some things in place to alleviate that pressure... the best way to recruit caregivers is to support your current caregivers really well."