To provide a structure capable of maintaining a work in a horizontal attitude regardless of an inclination of an endless power chain in conveying the work on an uphill slope.

Work supporting plates 11 are oscillatably supported on a plurality of carriages 5 running so as to follow the movement of the power chain. The respective plates 11 are preset so that its center of gravity may be positioned more forward than its oscillating center. On the conveyance side of the power chain 3 as an uphill slope, the respective plates 11 autonomously self-hold a horizontal attitude. On the return side of the power chain 3 as a downhill slope, the plates 11 autonomously take a retreat attitude parallel to the power chain 3, thus realizing space saving on the return side.