Bears Linebacker Matt Adams Arrested For Gun Possession

NFL linebacker Matt Adams' time in Chicago is off to a bad start -- the 26-year-old was arrested for gun possession on Thursday, TMZ Sports has learned.

We're told Adams -- who signed a 1-year deal with the Bears in April -- was questioned by cops around 6:45 PM after he was spotted near a Jeep that was reported stolen.

Adams allegedly claimed to have bought the car ... but when cops searched the vehicle, they found a loaded handgun in the center console and an extended mag in the trunk.

Adams was arrested and booked on misdemeanor unlawful use of a weapon -- carrying/possessing a firearm ... and was cited for having a high capacity magazine and metal piercing bullets.

We're told Adams had a permit for the gun ... but it was NOT issued by the state of Illinois.

Adams -- who is still in custody at the time of this post -- is due in court in August.

As for the car, we're told the owner did not want to press charges ... chalking the whole thing up as a misunderstanding.