To form a uniform thin film of a circulating liquid over an entire surface of a heat transfer pipe in an absorbing type heat exchanger even if a dripping of the circulating liquid from a header is disturbed.

A circulating liquid dripped to a heat transfer pipe 30 is guided by a guiding groove 31 formed along a longitudinal direction in the heat transfer pipe 30 in a longitudinal direction of the heat transfer pipe 30, changed into a uniform flow. Several guiding grooves 31 are spaced apart in a circumferential direction of the heat transfer pipe 30, thereby a uniform formation of the circulating liquid in its longitudinal direction is performed in sequence, thereby a uniform thin film of the circulating liquid is formed over an entire length of the heat transfer pipe 30.