This paper presents the investigation of the corrosion behavior of AISI316L samples prepared by laser-based powder bed fusion additive manufacturing (AM) method. Both AM and conventional stainless steel 316L samples were examined in NaCl 3.5% solution before and after the annealing process using Tafel curves, Electrochemical Impedance Spectroscopy, and X-ray diffraction. The results indicate that the AM parts have an improved corrosion behavior than the conventional wrought samples. Besides, the heat treatment process is found to further decrease the corrosion rate of the AM parts through the relieving of the residual stress. In contrast, the post annealing induced improvement to corrosion resistance for the wrought samples is due to the elimination of martensite phase which almost always exists after the plastic deformation during their production process.