The pivot point for the model (the black bone) would normally be at 0,0,0 of the modeling space. If your model is not constructed around 0,0,0 the pivot point woud appear outside it. Also if you had moved the black bone while in bones mode that would move the pivot point.
you can go in to bones mode in your model andmove the black bone to any point in your model. You may have to click on the background to make it appear.