Do you brush your tongue, use mouthwash, etc? The odor can come from your mouth but its possible it can be coming from your throat or even stomach. You may want to consult with your physician about it also if improved oral hygiene doesn't help.
The odor is usually caused by decaying food particles and bacteria in your mouth. You can improve bad breath with proper dental hygiene. If simple self care techniques don't solve the problem, you may want to see your dentist or doctor to be sure a more serious condition isn't causing your bad breath.