To obtain practical and large advantage by reducing a space required for a device compared with a conventional device and installing the device near an operator on a production line at an assembly site or the like, in a horizontal tray moving device for moving parts mounted on a dedicated tray between two positions.

The tray moving device includes: trays T; a tray circulating path 4 having two X-axis direction tray moving paths 5a, 5b parallel to each other and two Y-axis direction tray moving paths 6a, 6b positioned orthogonal to the X-axis direction tray moving paths on both ends of the X-axis direction tray moving paths and parallel to each other; and a tray driving means 20 for moving the trays in the tray circulating path 4. To prevent the trays from interfering each other in the Y-axis direction tray moving paths 6a, 6b, the tray moving device further includes a tray movement stopping means 30 provided with a main path 31 and an auxiliary path 32 for stopping the movement of the other trays in the X-axis direction tray moving paths 5a, 5b when one tray is positioned in the Y-axis direction tray moving paths 6a, 6b.