A device having electronic components mounted therein has a first electronic component having an external terminal on a first surface and a heat spreader on a second surface, at least one second electronic component that is placed in the direction of a second surface of the first electronic component, a flexible circuit board that is electrically connected to the first electronic component and at least one second electronic component, and at least the part to which at least one second electronic component is connected is located on the second surface side of the first electronic component, and a spacer that is located between at least part of the flexible circuit board and the second surface of the first electronic component. The spacer can prevent heat from the first electronic component from being directly transferred to the second electronic component.