Abstract: An IC receiving tray storage device is provided which is capable of securedly identifying the category of the tested ICs sorted for each category and received in the corresponding tray in the unloader section after end of test. Mounted to the tray storage is a casing comprising a generally rectangular base plate and a plurality of outer walls standing substantially upright and separately from each other on the base plate. A category identifying indicator is attached to at least one outer wall of the casing. This category identifying indicator indicates the category of ICs received in the tray. Also, in the base plate of the casing is formed an opening 71 through which a vertically movable unit is free to move. By the category identifying indicator, the category of the tested ICs received in the tray can be easily confirmed after the tray storage device has been taken out from the IC handler.