A belt drive apparatus, including, an endless belt to be laid across in a tensioned condition between supporting rollers and to travel being in pressure contact with or being separated from a body to receive the pressure contact, a pressure contact/separating state detection section to detect whether the endless belt is in the pressure contact with the body or separated therefrom, a belt position detection section to detect a position of the endless belt in a width direction thereof, a belt abnormality judging section to judge whether the endless belt is in an abnormal position based on a detection result obtained by the belt position detection section and one of judgment values which are set correspondingly to the pressure contact/separating state of the endless belt, and a belt drive control section to control a drive of the endless belt.