To provide a belt conveyance device used to convey parts to make a close inspection of precision parts, in particular, a belt conveyance device having: a conveyor steel-made belt having large width, and a small interval between a driving pulley and a driven pulley; a belt adjusting device for adjusting a running position of the belt with desired high precision; and a belt adjusting method.

The belt adjusting device which prevents meandering of the belt driven by a pulley and conveying articles to adjust its circumferentially moving position, is provided with: a position detection means for detecting a reference position in the circumferential direction of the belt per circumferential turn of the belt; a displacement detection sensor for detecting an amount of displacement for a reference position in the transverse direction of the belt at the reference position in the circumferential direction, and a pulley control mechanism for controlling arrangement of the pulley so as to make a difference in circumferential length between a belt edge on one side and a belt edge on the other side in accordance with the amount of displacement.