A loop heat pipe comprising: an evaporator configured to vaporize a working fluid; a condenser configured to liquefy the working fluid; a liquid pipe configured to connect the evaporator and the condenser ; and a vapor pipe configured to connect the evaporator and the condenser , and form a loop-shaped passage together with the liquid pipe , wherein each of the evaporator , the condenser , the liquid pipe and the vapor pipe includes a plurality of laminated metal layers (61-66) that form a pair of pipe walls of the evaporator , the condenser , the liquid pipe and the vapor pipe , respectively, wherein the plurality of laminated metal layers includes a first outermost metal layer , a second outermost metal layer and a plurality of intermediate metal layers (62-65) laminated between the first and second outermost metal layers , wherein the plurality of intermediate metal layers (62-65) includes inner wall surfaces (62s-65s) defining through holes penetrating the intermediate metal layers (62-65) and outer wall surfaces (62g-65g) opposite from the inner wall surfaces (62s-65s), and wherein the inner wall surfaces (62s-65s) of the intermediate metal layers (62-65), the first outermost metal layer and the second outermost metal layer form the passage of the working fluid, the loop heat pipe being characterized in that each of the plurality of intermediate metal layers (62-65) includes a recess (72A-75A) which caves in from a first principal surface (62a-65a) toward an approximate center along a thickness direction of the corresponding metal layer, at the outer wall surface (61g-66g) of each of the pair of pipe walls , each recess (72A-75A) of the intermediate metal layers (62-65) having a surface connecting the first principal surface (62a-65a) to the outer wall surface (62g-65g) of the corresponding intermediate metal layer (62-65). an evaporator configured to vaporize a working fluid; a condenser configured to liquefy the working fluid; a liquid pipe configured to connect the evaporator and the condenser ; and a vapor pipe configured to connect the evaporator and the condenser , and form a loop-shaped passage together with the liquid pipe , wherein each of the evaporator , the condenser , the liquid pipe and the vapor pipe includes a plurality of laminated metal layers (61-66) that form a pair of pipe walls of the evaporator , the condenser , the liquid pipe and the vapor pipe , respectively, wherein the plurality of laminated metal layers includes a first outermost metal layer , a second outermost metal layer and a plurality of intermediate metal layers (62-65) laminated between the first and second outermost metal layers , wherein the plurality of intermediate metal layers (62-65) includes inner wall surfaces (62s-65s) defining through holes penetrating the intermediate metal layers (62-65) and outer wall surfaces (62g-65g) opposite from the inner wall surfaces (62s-65s), and wherein the inner wall surfaces (62s-65s) of the intermediate metal layers (62-65), the first outermost metal layer and the second outermost metal layer form the passage of the working fluid, the loop heat pipe being characterized in that each of the plurality of intermediate metal layers (62-65) includes a recess (72A-75A) which caves in from a first principal surface (62a-65a) toward an approximate center along a thickness direction of the corresponding metal layer, at the outer wall surface (61g-66g) of each of the pair of pipe walls , each recess (72A-75A) of the intermediate metal layers (62-65) having a surface connecting the first principal surface (62a-65a) to the outer wall surface (62g-65g) of the corresponding intermediate metal layer (62-65). <EOS>