Microelectrochemical measurements and thermodynamic calculations were conducted to elucidate the electrochemical properties of CeS inclusions, and the relationship between those properties and pitting corrosion resistance was discussed. CeS inclusions containing ca. 20 at% Cr, (Ce,Cr)S, had better pitting corrosion resistance than (Mn,Cr)S inclusions. The pit initiation at the (Ce,Cr)S inclusion occurred at high potentials, outside the potential range in which the inclusion dissolved. On the other hand, in the case of (Mn,Cr)S inclusions, the pits were initiated in the dissolution potential range of the inclusions. Sulfur species and Ce3+ ions were estimated as the dissolution products from the (Ce,Cr)S inclusions. Stable pit initiation at the (Mn,Cr)S inclusions was inhibited in the Ce3+-containing NaCl solutions, implying that the Ce3+ ions released from (Ce,Cr)S inclusions improve pitting corrosion resistance.