A method of manufacturing a flaring-processed metal pipe from a hollow shell including a plurality of portions having different deformation resistances in a circumferential direction is provided, the method includes: among the plurality of portions, specifying a portion having a relatively small deformation resistance as a low deformation resistance section, and a portion having a relatively large deformation resistance as a high deformation resistance section; and press-fitting a pipe expansion punch into the hollow shell such that a thickness reduction rate of the low deformation resistance section is smaller than a thickness reduction rate of the high deformation resistance section.