HS2 CEO Simon Kirby has stepped down to take up a senior role at Rolls Royce.
He will join the company as chief operating officer, reporting to chief executive Warren East.
Kirby has been managing the controversial high-speed rail project for two and a half years.
He said it has been “a huge honour” to work on HS2 and said he has “absolute confidence” in the team being able to deliver the project.
Phase one of HS2 is expected to be completed by around 2026. It will cut through Oxfordshire and Buckinghamshire and reduce journey times between London and Birmingham by 32 minutes.
A second Y-shaped phase, taking the line to north-east and north-west England and beyond, is due to be completed by around 2032/33.
HS2 chairman David Higgins said the company will “miss his experience and leadership”. However Campaign group Stop HS2 said Kirby has got out before “anyone noticed how bad it really was”
“With HS2 deadlines constantly put back, spiralling costs, secret reports and devastating analyses of the project from every independent body which has investigated it, you can’t help think he is doing the same thing again, getting out before the true scale of the mess he has presided over is realised,” said campaign manager Joe Rukin.
“The departure of Simon Kirby will be a serious blow to those who champion HS2, though many of us are at a complete loss to see just exactly what it is he has done to justify his three-quarter of a million pay packet.”
HS2 Ltd is to start the process of finding Kirby’s successor.