PURPOSE: To efficiently produce a specified phase having high Tc of ≥100K when a Bi-Sr-Ca-Cu multiple oxide superconducting material is produced, by adding Pb or Pb oxide powder to starting materials for the superconducting material and sintering them.

CONSTITUTION: A compd. oxide having a compsn. represented by a formula BixSryCazCumOn (where 0.5≤x≤2.5, 0.5≤y≤2.5, 0.5≤z≤2.5 and 1.5≤m≤3.5) is used as a multiple oxide superconducting material. This Bi-Si-Ca-Cu-O superconducting material is generally produced by preparing Bi2O3, SrCO3, CaCO3 and CuO as powdery starting materials so as to satisfy the compsn. ratio of the desired multiple oxide, adding Pb or Pb oxide powder and successively subjecting them to molding, presintering, pulverizing, molding and sintering. The amt. of the Pb or Pb oxide powder added is preferably regulated to 0.003W0.4 atomic ratio to Cu in the resulting sintered body.