Circadian rhythm is a biological rhythm in a plant that has a 24-hour period, which affects the plant activities, such as metabolism processes, physiology processes, and plant behavior. Generally, Circadian rhythm has two factors affecting the synchronizing the biological clock: Light and temperature cycle. In our previous studies, plant motion monitoring systems based on leaf movement have been developed to determine the circadian rhythms of a regular plant under the normal condition. However, the performance of the system to monitor the plant rhythm under abnormal conditions relating to the biological clock, lighting interval treatment, does not establish yet. The objective of this study was to implement a plant motion monitoring system to study plant behavior with 16-hour and 12-hour lighting interval treatment. The plant's motion of Chili (Capsicum annum L.) was observed in a growth chamber equipped with an infrared camera and raspberry pi, which is used to take pictures continuously at certain intervals using top projection view. Periode of circadian rhythms phase, the amplitude of the plant were analyzed and compared. As a result, plant motion monitoring system could be used to monitor the circadian rhythm on Chili (Capsicum annum L.) with the variation of lighting interval (12-h and 16-h). The amplitude of 16-hour lighting has higher and the period shift indicated late oscilation comparing the 12-hour lighting. The higher amplitude and late in oscilation is accordance with previous studies that environmental cues, such as light, can reset the clock and can also affect the rhythm output clock.