According to one embodiment, a semiconductor storage device includes a housing, a first board, a heat generating component, an electronic component, and a thermal-conductive sheet. The housing has a first vent hole. The first board is accommodated in the housing. The heat generating component is mounted on the first board. The electronic component is disposed between the heat generating component and the first vent hole. The thermal-conductive sheet is provided to extend over the heat generating component and the electronic component, or provided to extend from a region positioned on a rear side of the heat generating component on the first board to the electronic component.