A loop heat pipe comprising: a pair of outermost metal layers (61, 63); an intermediate metal layer provided between the pair of outermost metal layers (61, 63); an evaporator configured to vaporize a working fluid to generate vapor; a condenser configured to liquefy the vapor of the working fluid; a liquid pipe connecting the evaporator and the condenser; and a vapor pipe connecting the evaporator and the condenser, and forming a loop shaped passage together with the liquid pipe, wherein the intermediate metal layer includes a pair of walls forming a part of a pipe wall of the evaporator, the condenser (20, the liquid pipe, and the vapor pipe, and a porous body provided between the pair of walls, wherein the intermediate metal layer includes a first surface opposing one of the pair of outermost metal layers (61, 63), a second surface opposing the other of the pair of outermost metal layers (61, 63), a plurality of first cavities, and a first projection between mutually adjacent first cavities, respectively formed at the first surface between the pair of walls, and a plurality of second cavities, and a second projection between mutually adjacent second cavities, respectively formed at the second surface between the pair of walls, wherein a first gap is formed between the first projection and the one of the pair of outermost metal layers (61, 63), wherein a second gap is formed between the second projection and the other of the pair of outermost metal layers (61, 63), characterized in that the porous body includes a first bottomed hole which caves in from the first surface of the intermediate metal layer but does not reach the second surface of the intermediate metal layer, a second bottomed hole which caves in from the second surface of the intermediate metal layer but does not reach the first surface of the intermediate metal layer, and a pore partially communicating with the first bottomed hole and the second bottomed hole, the first cavity has a depth shallower than a depth of the first bottomed hole, and the second cavity has a depth shallower than a depth of the second bottomed hole. a pair of outermost metal layers (61, 63); an intermediate metal layer provided between the pair of outermost metal layers (61, 63); an evaporator configured to vaporize a working fluid to generate vapor; a condenser configured to liquefy the vapor of the working fluid; a liquid pipe connecting the evaporator and the condenser; and a vapor pipe connecting the evaporator and the condenser, and forming a loop shaped passage together with the liquid pipe, wherein the intermediate metal layer includes a pair of walls forming a part of a pipe wall of the evaporator, the condenser (20, the liquid pipe, and the vapor pipe, and a porous body provided between the pair of walls, a pair of walls forming a part of a pipe wall of the evaporator, the condenser (20, the liquid pipe, and the vapor pipe, and a porous body provided between the pair of walls, wherein the intermediate metal layer includes a first surface opposing one of the pair of outermost metal layers (61, 63), a second surface opposing the other of the pair of outermost metal layers (61, 63), a plurality of first cavities, and a first projection between mutually adjacent first cavities, respectively formed at the first surface between the pair of walls, and a first surface opposing one of the pair of outermost metal layers (61, 63), a second surface opposing the other of the pair of outermost metal layers (61, 63), a plurality of first cavities, and a first projection between mutually adjacent first cavities, respectively formed at the first surface between the pair of walls, and a plurality of second cavities, and a second projection between mutually adjacent second cavities, respectively formed at the second surface between the pair of walls, wherein a first gap is formed between the first projection and the one of the pair of outermost metal layers (61, 63), wherein a second gap is formed between the second projection and the other of the pair of outermost metal layers (61, 63), characterized in that the porous body includes a first bottomed hole which caves in from the first surface of the intermediate metal layer but does not reach the second surface of the intermediate metal layer, a second bottomed hole which caves in from the second surface of the intermediate metal layer but does not reach the first surface of the intermediate metal layer, and a pore partially communicating with the first bottomed hole and the second bottomed hole, a first bottomed hole which caves in from the first surface of the intermediate metal layer but does not reach the second surface of the intermediate metal layer, a second bottomed hole which caves in from the second surface of the intermediate metal layer but does not reach the first surface of the intermediate metal layer, and a pore partially communicating with the first bottomed hole and the second bottomed hole, the first cavity has a depth shallower than a depth of the first bottomed hole, and the second cavity has a depth shallower than a depth of the second bottomed hole.