PURPOSE: To obtain a heat exchanger in which damage of a buffer plate can be prevented.

CONSTITUTION: A heat exchanger comprises an inner cylinder 2 arranged inside an inner body 1' arranged in an outer body 1, many heat transfer tubes 3 arranged between the bodies 1' and 2, an inlet 6 for feeding high temperature gas to an end of the body 1, and an end plate part 2c formed at the end of the cylinder 2 oppositely to the inlet 6. The part 2c is covered with a cylindrical liner 12, and a buffer plate 15 is provided at a lower end of the liner 12 to be easily disposed at a distant position from the inlet 6, i.e., a place where a high temperature gas passage is enlarged. Thus, the flowing speed of the gas collided with the plate 15 is reduced to prevent damage of the plate 15 due to fluid vibration.