Cornish Pirates director of rugby Ian Davies will leave at the end of the season because of "budget limitations".
He has been with the Championship side for seven years and took over in the role back in 2012.
Coaches Gavin Cattle and Alan Paver, who have both played for the side under Davies, will take charge next season.
"I'm absolutely devastated to be leaving, not only the Pirates but also Cornwall," said Davies in a statement on the club's website.
"I am certain Gavin and Alan will continue to do the fantastic job they are currently doing for us and I have assured them I am at the end of a telephone if they need a sounding board."
Davies has accepted a new role as director of rugby at Christ's Hospital School in Sussex, whose most high-profile graduate in recent times is England international Joe Launchbury.
"(There's been) a lot of soul-searching, a few tears between myself and my wife and then we came to the decision that ultimately I've got to move on," Davies added.
"Ever since I've been here there's been a promise of it (new stadium) being built, and it's still not happened yet - hopefully it does in the future because if it doesn't there are dark times ahead."
During his time with the Pirates, starting as forwards coach, the club won the inaugural British and Irish Cup in 2010 and reached the Championship play-off final in 2011.
"Delays to the 'Stadium for Cornwall' project have created budget pressures for the Cornish Pirates and as a consequence, playing budgets have had to be reduced for next season," said a club statement.
"Priority to signing players has been the key focus and the budget restrictions have imposed some challenging options - a consequence of these budget limitations is that Ian's time at the Pirates cannot continue beyond his current contract."
Davies took over as boss at the Mennaye from Chris Stirling, who returned to New Zealand four years ago.
The Cornish side are ninth in the second tier and reached the last four of the British and Irish Cup on Sunday with a 38-19 win over Doncaster.
"We're hugely indebted to Ian Davies for his major contribution during the Chris Stirling years and for his even greater contribution as director of rugby," added chairman Ian Connell.
"Everyone connected with the Cornish Pirates will wish Ian and his family every good wish as they relocate along the south coast to Sussex."