The opposition's claim comes after parents and the Tasmanian Principals Association yesterday called for public service laws to be changed so that schools could no longer go years on end with no permanent principal or experience a high turnover of them.

Opposition education spokesman Michael Ferguson said his party was willing to investigate the public service laws if it was elected, as effective leadership at school was needed "in order to implement our policies".

The policies include increasing literacy and numeracy results to the national average, extending high schools to year 12 and employing up to 105 new teachers.

A government spokesman said the Department of Education made every effort to provide continuity for schools.

"The government acknowledges the importance of continuity of leadership in schools while also recognising the right of school leaders to progress their careers by taking up new position," he said.

Bracknell Primary School Association member Angela Cresswell said the school had five principals in the past 18 months.

She said the last permanent principal retired in June and the position was only advertised last week.

"We're going to finish the year without even knowing who our principal will be next year," Ms Cresswell said.

She said the turnover of principals made it hard for students, teachers and parents.

"It's really stressful for parents because they want tradition and they want it to run smoothly," she said.

"It seems like every couple of months we're introducing ourselves to a new principal."

Beaconsfield Primary School had nine principals over nine years before a permanent position was offered in the past year.

Exeter Primary School is understood to have had six principals in six years.

The turnover occurs when one principal takes up another Education Department position and the vacated position is filled by someone else. This is compounded by public service laws that deem their positions must remain open for them to return.