To provide an article direction changing device and a direction changing method capable of automatically correcting displacement of a posture so as to prevent the displacement from occurring in a following article when a posture of an article whose direction is changed is displaced from a desired posture, if the direction of the posture of the article is changed during conveyance.

Speeds of both right and left conveying conveyors 28a, 28b arranged parallely so that a box B can be placed thereon are set to have a speed difference to change a direction by rotating a posture of the box B in a conveying direction, and the posture of the box B in the conveying direction is detected at a detection position at a middle of a conveying path. Based on detection results, when the posture of the box B is not a desired posture, preset contents of speed setting of the conveying conveyors 28a, 28b are corrected so that a posture of at least one of the articles whose postures are detected at the detection position and the articles conveyed after the article is coincide with a desired posture when the direction change is completed.