The present invention makes it easy to employ a floor surface aisle crossing a conveyance path in a conveyance system using a conveyance carriage 1 which travels on guide rails 7a and 7b laid on a floor surface 6 along the conveyance path, wherein at an aisle crossing section 14 in the conveyance path that the aisle on the floor surface crosses, a pit 15 is provided by digging down into the floor surface 6, and inside this pit 15, elevating guide rails 16a and 16b movable vertically parallel between a raised level at which the elevating guide rails connect the guide rails 7a and 7b before and after the pit 15 and a lowered level at which the upper surfaces of the elevating guide rails become flush with the floor surface 6 are disposed, and over the pit 15, a floor member 18 is laid so as to be flush with or substantially flush with the floor surface 8 while leaving elevating apertures for the elevating guide rails 16a and 16b.