Abstract: An object of the invention is to provide a server unit, which is so structured as to enable efficient cooling and which can be installed in great numbers in a server unit cabinet, and which comprises a cartridge type server unit 3 comprising (a) a printed circuit board 31 for a server unit, which is equipped with a central processing unit (CPU) and main memory and which serves as a computer with the supply of external electric power at constant voltage, (b) a heat sink 33 supported by the printed circuit board 31 for the server unit, and (c) a front panel 35 which supports the printed circuit board 31 for the server unit; wherein the front panel 35 supports the printed circuit board 31 so that a flat surface of the printed circuit board 31 is positioned vertically when the server unit 3 is accommodated, wherein a part of a heat sink 33 makes contact with highly heat-generating components mounted on the printed circuit board 31 via heat conduction means, and wherein a heat pipe 331 is provided to transmit heat