Aerial-feeding bats actively emit ultrasounds and capture large amounts of airborne insects a night. The microphone-array system allows us to know not only the positions where the bat emits sonar sounds (i.e., 3-D flight path) but how the bats dynamically control the acoustical field of view during searching and approaching target-prey. In this study, acoustic navigation behavior of the bats during natural foraging was measured using a large-scale microphone-array system in order to understand their acoustic sensing and path planning strategies. The microphone-array measurements revealed that Japanese house bat directed their sonar beams towards not only the immediate prey but also the next prey. From the mathematical modelling analysis, we found that the echolocating bats plan their flight path based on the positional information of both prey items. Recently, we have investigated the relationship between flight patterns, capture positions and foraging efficiency of Japanese large-footed bat during natural foraging above the pond. Further investigation from the viewpoint of the optimal foraging would reveal acoustic navigation strategy of the bats to efficiently search and approach prey items.