Two fifths of teachers predict they will not be working in education by 2024, a survey suggests.
The majority of teachers say the reasons for leaving are workload (62%), and 40% indicate it is due to the accountability regime.
A survey of 8,674 National Education Union (NEU) members in England, Wales, Scotland and Northern Ireland also found that more than a quarter (26%) with between two and five years' experience intend to leave education in the next five years.
For those with fewer than two years' experience, this drops to 15%.
While 40% of respondents said they would be out of the profession by 2024, 18% expect to be gone within two years.
One teacher said: "With a young family, and despite working part-time, I have come to realise that a job in education is not conducive to family life."
Another commented: "Working 70 hours a week for many years has meant my health and family life have suffered.
"I am getting out before the job kills me."
More than half of the respondents (56%) said their work-life balance has got worse, or much worse in the past year, 31% said it had stayed the same and just 12% said it had got better or much better.
The poll asked what would make the job better in the next 12 months.
One teacher replied: "Less assessment for pupils, it creates too much pressure on pupils and creates too much marking for teaching, which is taking away from valuable lesson planning, which would be much more beneficial for pupils."
Another said: "Trust being given back to the teachers. Less paper pushing and more focus on the children. Less emphasis on SATs results."
The survey also asked respondents what caused them stress.
Seventy-two percent said the amount of work expected of them, 58% said work-life balance, and 51% said external accountability.
The survey findings were released ahead of the NEU's annual conference in Liverpool debating a motion on teacher workload on Tuesday.
Kevin Courtney, joint general secretary of the NEU, said: "It is clear from our survey that the Government is doing a far better job of driving teachers out of the profession than they are solving the issue of excessive workload.
"Damian Hinds has made many of the right noises about fixing the problem, but he and his predecessors have achieved very little.
"The fundamental problem, as the results of our survey shows, is one of excessive accountability brought on by the DfE and Ofsted. The blame is at their door.
"So long as the main drivers of a performance-based system are still in place, schools will continue to be in the grip of a culture of fear, over-regulation, and a lack of trust."
He called for drastic action and a major Government rethink in order to stop the "haemorrhaging of good teachers from the profession".
A Department for Education spokeswoman said: "The Education Secretary has set out his determination to help teachers and school leaders reduce their workload and we have taken a range of actions to do this.
"It is an important element of our recently published recruitment and retention strategy.
"We have worked with school leaders and teachers to create a workload reduction toolkit, which provides practical advice and resources that schools can use rather than creating new ones from scratch.
"We are also tackling excessive data burdens in schools; simplifying the accountability system to target the associated burdens and working with Ofsted to ensure staff workload is considered as part of a school's inspection judgment."
