Robert Crawford has quit as chief executive of Scottish Enterprise to escape the "goldfish bowl" of the public eye.
Robert Crawford became chief executive in 2000
The 51-year-old has given 12 months notice that he intends to step down from the post in June 2004.
He said that by that time he would have completed what he set out to do at Scottish Enterprise (SE).
"The time will be right for me to pursue new challenges elsewhere," he said.
"The modernisation of Scottish Enterprise will be well under way and our landmark projects firmly established."
However, he admitted there had been "stresses" with some aspects of the job.
I have lived in a goldfish bowl for the past three-and-a-half years and I would like a less stressful life
He said some media coverage of his role had been unfair and that recent speculation about the performance of the agency had been "hurtful" - especially when it affected his family.
"I am 52 next week and I have lived in a goldfish bowl for the past three-and-a-half years and I would like a less stressful life," he said.
Mr Crawford was appointed chief executive in February 2000.
He was responsible for a radical restructuring of the organisation, which has seen large-scale job losses and the imposition of central control on the local enterprise companies.
However, he came under pressure over leaked memos which claimed that many of the organisation's targets would not be met.
Concerns have been raised about the agency
In March, Scotland's auditor general was asked to investigate the use of consultancies by Scottish Enterprise.
The move followed a BBC Scotland investigation and press reports about the agency's financial management and use of European funds.
Mr Crawford denied the claims and said an Audit Scotland report would show that SE had met 21 of its 22 targets.
He said the organisation had gone through a "painful but necessary" period of change.
"Scottish Enterprise is now geared towards helping Scotland meet the many new challenges it faces," he said.
The organisation's chairman, Sir Ian Robinson,
said Mr Crawford would remain in post until the new chief executive was appointed.
I am grateful for his very considerable contribution to preparing Scotland's economy for the challenges ahead
"Robert has been a hugely talented and influential chief executive and the driving force behind many of the improvements made across the network," he said.
"However, as with all talented individuals, he has a desire to move on and take on new challenges.
"Robert leaves the organisation in good shape to hand over the reigns to his successor."
First Minister Jack McConnell said he was disappointed to hear of Mr Crawford's decision.
"With our support, Robert Crawford has ensured more consistent support for business, a more streamlined organisation and he has driven innovative projects such as the Intermediary Technology Institutes," he said.
"I am grateful for his very considerable contribution to preparing Scotland's economy for the challenges ahead and I would hope to call on his advice and experience again in the future."
The Scottish Conservatives' enterprise spokesman, Murdo Fraser, said Mr Crawford's departure had left the government's enterprise policy in "disarray".
He said it created an opportunity to restructure and refocus Scottish Enterprise and use part of its budget to reduce business rates.