To solve a problem that many blowers generate intense noise since it is necessary to prepare a blower for each of a plurality of units when cooling the heat source of a wiring board carrying electronic circuit elements housed in the unit, as each unit to be stored in a cabinet (rack) is housed in a sealed device casing in a cabinet type multiple stage computer storing apparatus.

A cooling structure is installed in a cabinet by making a device casing which houses a wiring board carrying a plurality of electronic circuit elements to be stored in the cabinet type multiple stage computer storing apparatus as tray type and disusing an individual cooling structure using a blower installed directly for every heat source by exposing the heat source from the unit and preparing a cooling structure in the cabinet. Since common cooling wind can be used by exposing the heat source from the unit by making the plurality of units of the cabinet type multiple stage computer storing apparatus, a tray type, the cooling structure which is installed directly to each heat source of the wiring board can be removed, and as a result, quantity of the blower is reduced and the cooling structure can be simplified and the noise due to the blower is reduced.