The present study aimed to investigate inter- and intraobserver error in order to clarify whether mastication time and frequency can be accurately measured using video observation.   Mastication time and frequency were measured from video camera footage of four subjects. Interobserver error was calculated based on differences in measurement values between two observers′ single observations of the four subjects and analyzed using intraclass correlation coefficient. Intraobserver error was calculated based on differences in measurement values from one observer′s observations of the four subjects repeated three times and analyzed using one-way analysis of variance and intraclass correlation coefficient.   Intraclass correlation coefficient was ≥0. 9 for both inter- and intraobserver measurements of mastication time and frequency, demonstrating small inter- and intraobserver error. No significant differences in mean values were observed for intraobserver error with one-way analysis of variance.   The present findings indicate that inter- and intraobserver differences in measurement values for mastication time and frequency based on video observation are small, suggesting that one measurement by one observer is likely to provide representative values for mastication time and frequency during video observation.