The adhesion of epoxy resin and poly(p-phenylene sulfide) (PPS) is investigated using density functional theory. This study investigated the unoxidized and oxidized (100), (110), and (010) surfaces of PPS, with (110) and (010) surfaces having the highest and lowest adhesive strengths, respectively. Surface oxidation increased the adhesive strength, particularly that of surfaces with initially low strength. The change in surface roughness by oxidation also affected the dispersion interaction, decreasing for the (100) and (110) surfaces and increasing for the (010) surface. The contribution of both interactions resulted in comparable adhesive strength for all oxidized surfaces. These findings provide insights for adhesion to PPS materials.