A belt-conveyor device includes a detecting unit that detects a belt position in a width direction of the endless belt for a plurality of times within more than a cycle of the endless belt, the width direction being a direction orthogonal to direction of travel of the endless belt; an average calculating unit that calculates an average belt position from the belt positions detected by the detecting unit; a storing unit that stores therein a plural sets of correction values and belt positions; and a meander correcting unit that corrects meander of the endless belt based on a correction value that corresponds with the average belt position in the storing unit.