A loop heat pipe, comprising: an evaporator configured to vaporize a working fluid; a condenser configured to liquefy the working fluid; a liquid pipe that connects the evaporator and the condenser to each other; and a vapor pipe that connects the evaporator and the condenser to each other, wherein the condenser comprises: a first outer metal layer; a second outer metal layer; and an inner metal layer that is provided between the first outer metal layer and the second outer metal layer, and having a flow channel through which the working fluid flows; wherein the first outer metal layer comprises: a first inner face that contacts the inner metal layer; a first outer face opposite to the first inner face in a thickness direction of the first outer metal layer, and wherein the second outer metal layer comprises: a second inner face that contacts the inner metal layer; a second outer face opposite to the second inner face in a thickness direction of the second outer metal layer; characterized in that the first outer metal layer comprises a plurality of first recesses that are provided in the first outer face so as not to overlap the flow channel in plan view and that are arranged side by side in a certain direction, the second outer metal layer comprises a plurality of second recesses that are provided in the second outer face so as not to overlap the flow channel in plan view and that are arranged side by side in the certain direction, wherein the plurality of second recesses and the plurality of first recesses do not overlap each other in plan view. an evaporator configured to vaporize a working fluid; a condenser configured to liquefy the working fluid; a liquid pipe that connects the evaporator and the condenser to each other; and a vapor pipe that connects the evaporator and the condenser to each other, wherein the condenser comprises: a first outer metal layer; a second outer metal layer; and an inner metal layer that is provided between the first outer metal layer and the second outer metal layer, and having a flow channel through which the working fluid flows; wherein the first outer metal layer comprises: a first inner face that contacts the inner metal layer; a first outer face opposite to the first inner face in a thickness direction of the first outer metal layer, and wherein the second outer metal layer comprises: a second inner face that contacts the inner metal layer; a second outer face opposite to the second inner face in a thickness direction of the second outer metal layer; characterized in that the first outer metal layer comprises a plurality of first recesses that are provided in the first outer face so as not to overlap the flow channel in plan view and that are arranged side by side in a certain direction, the second outer metal layer comprises a plurality of second recesses that are provided in the second outer face so as not to overlap the flow channel in plan view and that are arranged side by side in the certain direction, wherein the plurality of second recesses and the plurality of first recesses do not overlap each other in plan view. a first outer metal layer; a second outer metal layer; and an inner metal layer that is provided between the first outer metal layer and the second outer metal layer, and having a flow channel through which the working fluid flows; wherein the first outer metal layer comprises: a first inner face that contacts the inner metal layer; a first outer face opposite to the first inner face in a thickness direction of the first outer metal layer, and a first inner face that contacts the inner metal layer; a first outer face opposite to the first inner face in a thickness direction of the first outer metal layer, and wherein the second outer metal layer comprises: a second inner face that contacts the inner metal layer; a second outer face opposite to the second inner face in a thickness direction of the second outer metal layer; a second inner face that contacts the inner metal layer; a second outer face opposite to the second inner face in a thickness direction of the second outer metal layer; characterized in that the first outer metal layer comprises a plurality of first recesses that are provided in the first outer face so as not to overlap the flow channel in plan view and that are arranged side by side in a certain direction, the second outer metal layer comprises a plurality of second recesses that are provided in the second outer face so as not to overlap the flow channel in plan view and that are arranged side by side in the certain direction, wherein the plurality of second recesses and the plurality of first recesses do not overlap each other in plan view.