To prevent a brazing filler metal from flowing out to the external surface of an end plate 5 on brazing in a plate-type heatsink formed by laminating a large number of flat plates.

Intermediate plates 4 having same-shaped outer peripheries are laminated on each other, and end plates 5 with outer peripheries one size larger than the outer peripheries of the intermediate plates 4 are disposed in both upper and lower ends of the laminate. The laminate and the end plates 5 are brazed and fixed integrally to each other.