In this study, we measured work functions on various materials (i.e., metals and semiconductors) using Kelvin probe force spectroscopic method. Since the Kelvin probe force microscopic (KPFM) method allow to determine the work function difference between the metallic tip and unknown work function samples, it is very important that work function of the tip is accurately defined. Therefore, all the conductive tips were calibrated with a freshly cleavaged highly oriented pyrolytic graphite (HOPG). Work function measurements on various materials are conducted by using these calibrated tips. The values of work functions of metal films (i.e., Au and Pt) obtained in this method were found to correspond to the values reported in the literature, but those for semiconductor materials (i.e., n-, p-type Si and ITO films) show some deviations from their work functions which would be found in the literature. Surface electronic band bending and geometry of the tip could affect the differences in work functions measured by KPFM technique.