A brazing method includes assembling a first member and a second member, the first member including a base plate made of a ferrous material and a diffusion suppressing layer laminated on the base plate and made of a Ni—Cr alloy including more than about 15% and less than about 40% of Cr, the second member being disposed on the first member with a brazing material of a Cu—Ni alloy including more than about 10% and less than about 20% of Ni therebetween, and maintaining the temporary assembly at a temperature of more than about 1,200° C. to fuse the brazing material and diffuse Ni atoms and Cr atoms into the fused brazing material to form the braze joint, causing the resulting brazing material to have an increased melting point due to the Ni and Cr contents of the braze joint to self-solidify the braze joint, and then cooling the resulting assembly.