The number of people training to be teachers has dropped by 40 percent, creating what the Education Minister has called a "ticking time bomb" for retiring teachers.
Latest Education Ministry figures show between 2010 and 2016 the number of people enrolled in teacher training dropped by 5690, from 14,585 to just 8895.
The number of teacher trainees dropped in early childhood education, as well as primary and secondary teachers.
Over the same time the population grew by 400,000.
Auckland secondary school principals have warned they face a shortage of 3000 teachers over the next 10 years if urgent action isn't taken to get more people into classrooms.
Mr Hipkins said the shortage was staggering and he blamed poor planning by the National government.
He said the government's $9.5 million teacher supply package would help but more was needed.
"It is going to require additional investment...it's part of the budget process and we're going through those negotiations at the moment," he said.
Mr Hipkins said there were not enough graduates to replace retiring teachers and the government was working to make the teaching profession more attractive.