Adam Shankman -- the guy who directed "Hairspray" and several eps of "Glee" -- has reportedly checked into rehab.
Shankman's rep told US Weekly ... "Adam Shankman is currently seeking treatment in a rehabilitation center. His friends and family support him and wish him well on his journey to recovery."
The rep did not say WHY the 49-year-old is in rehab.
Seems Shankman is following his friend Zac Efron's lead -- as we previously reported, Zac sought treatment TWICE earlier this year for cocaine.
Shankman was also tight with "Glee" star Cory Monteith ... who died back in July after struggling with substance abuse.