A heat pipe, includes; an outer tube including first and second ends, the first end closed air tight; a box connected to the second end, a cross-sectional area of the box perpendicular to the outer tube central axis is larger than a cross-sectional area of the outer tube perpendicular to its axis; an inner tube positioned in the outer tube, a central axis of the inner tube parallel to the outer tube central axis, including third and fourth ends, the third end closer to the first end than the fourth end and open in the outer tube; a partition tube including fifth and sixth ends widening from the fifth end toward the sixth end, the fifth end connected with the fourth end, part of the sixth end connected on an inner surface of the box; and fluid in a space formed by the outer tube and the box.