In the present invention, through the provision of a tray placing rack for storing trays in multi steps, the trays accommodating electronic parts after inspection are received in the racks and through the provision of a tray stacking rack above the tray placing rack, an empty tray emptied by having been inspected of the electronic parts before inspection at an inspection stage is stacked on the tray stacking rack. When a certain tray is filled with electronic parts after inspection and is discharged, an empty ray is taken out from the tray stacking rack and the empty tray is fed to the rack position of the discharged tray to permit re-use of empty trays.