Abstract: The present invention provides a Bi2223 oxide superconductor composed of Bi, Pb, Sr, Ln, Ca, Cu, and O, wherein the Ln is at least one selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and the composition ratio of Sr to Ln is a composition ratio described below. The Bi2223 oxide conductor has a high critical current density in a magnetic field at low temperature and is capable of maintaining a high critical current density in a self magnetic field even at 77 K. Sr:Ln=(1?x):x (wherein 0.002?x?0.015) Also, the present invention provides a method for producing the Bi2223 oxide superconductor, the method including a step of ionizing a material containing elements, which constitute the Bi2223 oxide superconductor, in a solution; and a step of removing a solvent and causing a thermal decomposition reaction by spraying the solution into a high-temperature atmosphere to produce a powder containing atoms constituting the oxide superconductor.