The adhesion of Pt/Ti thin films on SiN x /Si substrates with respect to the substrate pretreatment and annealing ambient was investigated using the adhesive tape test, the peel test, and the scratch test. Pt/Ti thin films were deposited a DC magnetron sputtering system. The in situ Ar+ RF plasma treatment was more effective in enhancing adhesion between the Pt/Ti thin films and the SiN x /Si substrate than chemical cleaning. After annealing in an oxygen ambient, the adhesion of the Pt/Ti/SiN x /Si specimen was degraded. This adhesion degradation was attributed to the depletion of the Ti adhesion layer due to the formation of the rutile TiO2 phase.