The present invention relates to a powder mixture for iron-based powder metallurgy which is obtained by mixing an iron-based powder and at least one kind of powders selected from the group consisting of a Ca—Al—Si-based composite oxide powder and a Ca—Mg—Si-based composite oxide powder, in which with a peak height of a main phase exhibiting the highest peak intensity by X-ray diffraction as 100, the composite oxide powder has a relative height of 40% or less, with respect to the main phase, of a peak height of a second phase having the second highest peak intensity.