A shutter unit includes a plurality of shutters that are grouped into groups corresponding to one of a plurality of fans, the grouped shutters being arranged beside one another and positioned on a leeward side or a windward side of the corresponding one of the plurality of fans, the grouped shutters being capable of pivoting between an open position and a closed position, the plurality of fans being for sending wind to an inside of an electronic apparatus casing; a coupling member that couples the grouped shutters together so that the grouped shutters are pivotable; and a retaining member that retains the grouped shutters in a state of being in the open position and inclined with respect to a flow direction of returning wind returning from the inside of the electronic apparatus casing toward a side of the plurality of fans.