To provide a multitube type heat exchanger being improved in the strength and durability of the brazed part of a tube sheet and a heat transfer tube and being abundant in reliability and excellent in the quality.

The multitube type heat exchanger having a structure wherein a barrel tube, the tube sheets provided in the vicinity of the opposite end parts of the inner wall of the barrel tube, a heat transfer tube group supported by the tube sheets and end part caps provided at the opposite end parts of the barrel tube are integrated by brazing respectively. Herein the inner and outer end faces of at least one end of the heat transfer tube are brazed to the tube sheet.