The 67-year-old Tost took charge in 2005 and led the team, then branded as Toro Rosso, to its first victory at the 2008 Italian Grand Prix with future four-time world champion Sebastian Vettel behind the wheel.
Tost steps down as AlphaTauri F1 chief after 18 years
At a glance
PARIS (AFP) -- Franz Tost will step down as AlphaTauri team chief at the end of the season after 18 years at the helm of the Formula One outfit which first nurtured the talent of reigning world champion Max Verstappen.
The 67-year-old Tost took charge in 2005 and led the team, then branded as Toro Rosso, to its first victory at the 2008 Italian Grand Prix with future four-time world champion Sebastian Vettel behind the wheel.
Under Tost's watchful eye, Pierre Gasly delivered victory in AlphaTauri colours for the first time, also at Monza in 2020.
"First of all, I would like to thank Dietrich Mateschitz, who gave me the incredible opportunity to be team principal of Toro Rosso and AlphaTauri for the past 18 years," Tost said on the team's Instagram feed.
"It has been a true privilege to lead the team for such a long period and a great pleasure to work with so many motivated and skilled people, who share my passion for Formula One."
Laurent Mekies, currently sporting director at Ferrari, will join AlphaTauri as its new team principal at a date to be confirmed, added the team.
Former FIA executive Peter Bayer will join as chief executive later this year.
After three races this season, AlphaTauri are ninth of 10 teams in the constructors' championship with one point secured by Yuki Tsunoda.
Teammate Nyck de Vries is pointless and currently rock bottom of the drivers' standings.