Karl Krikken's 27-year Derbyshire career has come to an end following a restructuring of the club's coaching set-up.
Krikken leaves his post as head coach two weeks after the club announced the entire coaching team would be forced to re-apply for their jobs following their relegation from the first division last season.
A club statement said Krikken had decided to seek "opportunities elsewhere".
Derbyshire made an immediate return to the second division after Krikken had led them to promotion in his first season in charge.
"I would like to thank the off-field staff, groundsmen, coaches, players and members for all their help and support during my time at Derbyshire," Krikken, who enjoyed a 17-year playing career at the County Ground, said in the statement.
"I have thoroughly enjoyed my time at the club, firstly as a player and then as a coach.
"In the last couple of years during my tenure as head coach, I have been immensely proud to lead a team of great lads to the first trophy for Derbyshire in 19 years and last year to our highest championship finish since 1996."
Derbyshire plan to introduce an "elite cricket performance" structure from January, to be headed by an elite cricket performance director.
The county indicted earlier this month that they were looking at best practice used by other teams - notably England - with the restructre recommended following a review by the club's supervisory board.
Chairman Chris Grant thanked Krikken for his long-term contribution.
He said: "It's sad that Karl's time at the club has come to an end and we thank him for his contribution to drafting the new elite player pathway, we respect his decision to seek opportunities elsewhere and we wish him all the very best for the future."
"Our recruitment process will now continue and we are confident that the new elite performance structure will enhance our chances of success in the years to come across all three domestic competitions."