Heat pipe, and cooling mechanism for rotating machine

A heat pipe provided with a tubular container having a working fluid in the interior and capable of rotating about a central axis that extends in the longitudinal direction. The container has a first end and a second end, which are the two ends in the longitudinal direction, and, in sequence in the longitudinal direction from the second end to the first end: a heat dissipation part including the second end, the inside diameter of at least a part of the container increasing in the direction from the second end to the first end, and the heat dissipation part being configured so as to release heat to the exterior; a heat insulating part adjacent to the heat dissipation part; and a heat reception part adjacent to the heat insulating part, the heat reception part being configured so as to receive heat from the exterior.