A heat pipe which, even though small in size, can transmit heat more easily from a device to be cooled to refrigerant and reliably continue to cool the device to stably maintain its operating conditions. The heat pipe has a better heat radiation effect than conventional ones. A cooling section body (25) has a vapor diffusion flow path (42) extending to the periphery of the cooling section body (25) and also has a capillary tube flow path (41) formed in the vapor diffusion flow path (42) and in a region (47) where recesses face to each other. A recess (6) having a small wall thickness is formed in the cooling section body (25), and an LED chip (2) is mounted in the recess (6). In the heat pipe (50), the small wall thickness of the recess (6) makes heat transmission from the LED chip (2) to the refrigerant easier, and the heat causes continuous circulation of the refrigerant (W) to be reliably repeated. Latent heat produced when the refrigerant (W) evaporates reliably absorbs heat from the LED chip (2), and as a result, emitting conditions of the LED chip (2) is stably maintained.