PURPOSE: To manufacture angle material having an internal angle of nearly right angles by working a metallic flat plate into an intermediate material equal nearly to right angles and rolling the internal angle part as it is heated locally when a specified angle material is manufactured.

CONSTITUTION: In the angle material to be manufactured, α, angle of the internal angle part is 85-90 degrees and M, length of the internal angle part is 0.5-2.0 times the plate thickness L. In that case, when the angle of the internal angle part is finished to 85-90 degrees, it is worked as it is heated locally. Consequently, the internal angle part can be easily worked nearly to right angles without generating thermal strain and stress in the angle material 1. Accordingly, matching and adhesion to the building material are improved.