A loop heat pipe includes a metal layer stack of outermost metal layers and intermediate metal layers. The metal layer stack includes an evaporator that vaporizes a working fluid, a condenser that liquefies the working fluid vaporized by the evaporator, a vapor pipe connecting the evaporator to the condenser, and a liquid pipe connecting the condenser to the evaporator. The vapor pipe includes two pipe walls defining a flow passage of the vapor pipe and joint beams arranged at different positions along the flow passage. Each of the joint beams joins the two pipe walls to each other. Each of the intermediate metal layers includes one of the joint beams. Each of the joint beams includes a side surface that is inclined.