a step of preparing raw material powder containing powder of inorganic material;

a step of producing a powder compact having a high-density portion with a relative density of 95% or more and a low-density portion with a relative density of less than 93%, with a difference in relative density between the high-density portion and the low-density portion being 3% or more, by compressing the raw material powder injected into a mold;

a step of producing a machined compacted part by machining at least the high-density portion of the powder compact; and

a step of sintering the machined compacted part to make a sintered body,

wherein a perimeter shape of a cavity constituted by the mold in a cross-section perpendicular to an axial direction of the mold is such than a maximum stress applied to an inner perimeter surface of the mold during a compacting process using the mold is less than or equal to 2.6 times an imaginary maximum stress that is applied to an inner perimeter surface of an imaginary mold during a compacting process using the imaginary mold, the imaginary mold having an imaginary cavity that has a same area as the cavity and that has a circular perimeter shape.