A-site-ordered perovskite-structure oxides with Mn and V at A' and B sites, respectively, were synthesized by using a high-pressure method. Valence-state analyses revealed that the A-site substitution modulated the valence states of the Mn ions at the A' site and V ions at the B site sequentially. By changing the A-site ions from Na+ to Ca2+ and from Ca2+ to La3+, the valence distribution changed site-selectively from Na+Mn32.33+V44+O12 to Ca2+Mn32+V44+O12 and to La3+Mn32+V43.75+O12. The electrons of the A'-site Mn were localized and contributed to the magnetic properties, that is, spin-glass-like behavior in NaMn3V4O12 and antiferromagnetic behavior in CaMn3V4O12 and LaMn3V4O12. The valence electrons of the B-site V, in contrast, were delocalized, as could be seen from the low resistivity of the samples. The delocalized electrons at the B-site V did not correlate with the localized spins at the A'-site Mn.