Provided are a method for manufacturing MgB2 superconductor by pressure molding a mixture of Mg powder or MgH2 powder and B powder and heat-treating the mixture, the method including (I) a step of adding a polycyclic aromatic hydrocarbon to the B powder, while heating the mixture to a temperature higher to or equal to the melting point of the polycyclic aromatic hydrocarbon at the time of this addition, and thereby covering the surface of the B powder with the polycyclic aromatic hydrocarbon; and (II) a step of mixing the B powder having the surface covered with the polycyclic aromatic hydrocarbon, with the Mg powder or the MgH2 powder, or a step of combining the B powder having the surface covered with the polycyclic aromatic hydrocarbon, with an Mg rod; and an MgB2 superconducting wire which has high critical current density (Jc) characteristics and less fluctuation in the critical current density (Jc).