Almost 1,000 schools struggled to find a new headteacher last year, as the number of posts advertised hit a three-year high.
In 2004, nearly 2,700 schools had to look for a new head, with a third of posts having to be re-advertised, a study has found.
There were 418 vacancies in secondary schools, up from 387 a year earlier, despite an increasing number offering six-figure salaries. In primaries, there were 2,125 vacancies.
It means that about 11 per cent of secondaries in England and Wales were looking for a new head. However, this remains below the record level set in 2000 when there were 446 vacancies.
John Howson, of Education Data Surveys, who analysed the figures, said the retirement boom "was likely to keep the total high for the next few years".
He predicted the first pound;120,000 headship in a mainstream secondary this year. Already heads can earn five times more than their most junior teaching staff.
Pay for primary heads is also creeping up, with the first salaries of more than pound;70,000 recorded last year. Similar sums would become more common as schools started to provide more community services as part of the extended day, the study said.
For the second consecutive year, a record number of advertisements for special schools and pupil referral unit heads was recorded with 151 vacancies, up from 127 in 2001, and about 10 per cent of the total.
January, February and March were the busiest months of the year, with 1,225 (46 per cent) of all posts being advertised, and a further 11 per cent in September.
There were 119 re-advertisements for posts in secondary schools, representing 27 per cent of the total, while 37 per cent of primaries did not find the right candidate first time around.
Church schools, those in London and small rural schools were most likely to have to readvertise. Among special schools, 38 per cent readvertised.
Professor Howson said: "This is a new and shocking record.
"For over one in three primary schools not to be able to appoint a headteacher when they advertise results in a significant waste of time and money.
"More help ought to be on offer to governing bodies to ensure that they undertake appropriate recruitment practices."
Magnus Gorham, assistant secretary in the salaries and pensions department of the National Association of Head Teachers, said some primaries were not offering high enough salaries.
"Some labour under the misapprehension they can offer the same as the previous head earned, and that is why schools have to re-advertise," he said.
"We remain very concerned about where the next generation of heads is going to come from, because being a head is not that attractive a prospect."
John Dunford, general secretary of the Secondary Heads Association, said:
"Being a head is considered a high-risk occupation, whereas it used to be a job for life. Because of the age profile of the profession, things can only get worse."