Anthony May said the council was committed to improving services
Nottinghamshire's child social care department has "significant weaknesses" in its handling of child protection cases, an Ofsted report has found.
The council was under-performing in identifying children at risk and failed to act quickly enough, inspectors said.
It was also revealed that most social workers were not receiving the necessary support with large workloads.
Funding has been approved to ensure measures are in place to improve child protection in the county, it added.
Ofsted - the body which regulates the care of children and young people - carried out the unannounced inspection last month.
The report found responses to child protection referrals did not not meet statutory guidance and did not ensure that children were adequately safeguarded.
It also said: "Referrals are sometimes closed prematurely without children being seen."
The report noted: "Most social workers, including recently qualified social workers, are carrying high caseloads that include a number of pieces of complex work that they are unable to complete within national guidance and to timescale."
However, the report recognised social workers and managers were striving to improve the service.
The Ofsted report went on to confirm funding had been approved to ensure measures were in place, including the recruitment of more staff, to improve child protection in the county.
Anthony May of Nottinghamshire County Council's Children and Young People's Services said: "Child protection and safeguarding the children and young people of Nottinghamshire is absolutely the top priority for this council.
"And notwithstanding the significant increase in workload in these highly pressurised services we are committed to improving them."