In this study, we evaluated a phototaxis of pillbugs(Armadillidium vulgare) by using a behavior measurement system consisting of an omnidirectional motion compensation mechanism and a cylin-drical LED display. At the first, to validate the phototaxis of pillbugs against unidirectional light stimulation, we conducted an experiment under continuous light stimulation from one direction for 30 minutes. Subsequently, to evaluate phototaxis performance under the condition that the direction of light stimulus changes alternately, we experimented under three iteration cycles conditions (160 s, 40 s, 10 s). Our results revealed that the pillbugs moved significantly in the direction of weak light intensity, and it suggested that the pillbugs has negative phototaxis. Moreover, we showed that the negative phototaxis became the strongest when the iteration cycle is 160 s, and the negative phototaxis tended to weaken as the iteration cycle became shorter. Also, when the iteration cycle is 10 s, an increase in residence time is found, suggesting that does not necessarily take the routine response behavior according to the situation.
