A slat conveyor has a plurality of slat bodies supported between a pair of left and right driving endless turning bodies by concentric horizontal support shafts and has a pair of front and rear guide rollers supported to a guide rail laid on each of upper and lower horizontal path sections. A U-turn guiding mechanism at both ends includes the guide rollers, a slat body posture controlling rotating body, and a drive mechanism for the rotating body. The rotating body has the same turning radius as that of the horizontal support shaft on a U-turn path section, and includes an engaging portion for positioning and turning the guide rollers. The drive mechanism drives the rotating body such that the engaging portion is turned in the same direction and at the same speed as the turning speed of the horizontal support shaft on the U-turn path section.