PURPOSE: To stack a number of trays without causing horizontal and vertical disengagement from one another to facilitate the storage and transportation thereof or permit the setting thereof on an automatic mounting device.

CONSTITUTION: The sides of each tray 1 are provided at the upper and lower parts thereof with interengageable raised edges 3 and depressed edges 4 to prevent each adjacent tray 1 from lateral movement and at least a pair of opposed sides of each tray are provided with interengageable locking pieces 13 to interlock each adjacent tray 1. When the trays are set on an automatic mounting device, the locking pieces 13 are released easily by pressing the trays in the lateral direction. This prevents the disengagement of the trays 1 from one another and hence the falling off of an electronic component and the bending of the lead. Morever, the attachment and detachment of the individual trays is easy in the automatic mounting device.