Justin Bieber -- Cruising on the Board in Beverly Hills Ghost Town (VIDEO)

Justin Bieber didn't have a care in the world as he cruised at high speed on his skateboard, in the middle of an empty Bev Hills street.

Justin was just like any ol' skate rat as he zoomed past the TMZ Hollywood Tour bus at around 9 PM.

The Biebs has developed mad skills on the board since we last saw him ... straight lining a steep decline into a parking garage. No worries about speed wobbles ... he's in control.

Stopping is the hardest part and we don't know how he handled that, but he's definitely still alive.