Adam Shankman -- 'Hairspray' Director Enters Rehab

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.