Abstract: A counter-stream-mode oscillating-flow heat transport apparatus accommodates a change in volume of a liquid while preventing reduction in heat transport capability. A flow path and a buffer tank are placed in communication with each other via a throttle such as a capillary tube. This prevents a channel connecting the flow path and the buffer tank from having an excessively reduced channel resistance (flow path resistance). This prevents the fluid in a heat transport device assembly (the flow path) from only going back and forth between the heat transport device assembly and the buffer tank without experiencing liquid (pressure) oscillations in the heat transport device assembly. Accordingly, the liquid in the heat transport device assembly is prevented from being reduced in amplitude of oscillation, thereby preventing degradation in heat transport capability of the counter-stream-mode oscillating-flow heat transport apparatus.