The effect of low tempering in a temperature range of $150{sim}400^{circ}C$ on corrosion resistance in 420J2 stainless steel austenitized at $1000^{circ}C$ was investigated by the application of salt spray test, electrochemical pitting test in 3.5% NaCl solution and DL-EPR test for intergranular corrosion in 0.5M $H_2SO_4$+0.01M KSCN solution. In salt spray test, good corrosion resistance was obtained in a tempering temperature range of $150{sim}250^{circ}C$. Pitting potential was increased to the tempering temperature of $250^{circ}C$, but decreased with the increase of temperature up to $400^{circ}C$ And it was thought that the degradation of pitting corrosion resistance showed at the tempering temperature of around $400^{circ}C$ was due to the precipitation of $Cr_7C_3$ of $M_7C_3$ type. The degree of sensitization showed increasing tendency with the increase of tempering temperature, and also Cr depletion phenomena were observed in the vicinity of grain boundary.