An interior cooling structure according to the present invention includes a frame in which a plurality of circuit board modules are stacked, with electronic components mounted on the plurality of circuit board modules by being classified by function; an external housing which covers the frame together with the plurality of circuit board modules; a plurality of cooling devices which reduce temperature rises in the external housing caused by heat produced by the plurality of circuit board modules; and a heat generating region a partitioned in such away as to enclose a circuit board module which has the highest total power consumption out of the plurality of circuit board modules, wherein the plurality of cooling devices are arranged in such away as to reduce temperature rises in the heat generating region by displaying capacity higher than capacity of each of the cooling devices.