The conventional electrophysiological method revealed some aspects of neural network for animal behavior. But it was inappropriate for recording activities of many neurons simultaneously. For the purpose of the multi-cell recording from Aplysia central nervous system, we used the calcium imaging method. Spike activities could be recorded from-30 neurons simultaneously. We also demonstrated that the firing properties of individual neurons, such as frequency or period, and the phase-locked firing patterns of these neurons could be easily detected. Moreover, combining this method with the electrophysiological method, we could identify several motor neurons concerned with the feeding behavior of this animal.