Numerous studies in biological and chemical processes have been conducted in Lake Suwa, only a few of which were concerned with physical processes that strongly affect a lake' s biochemical dynamics. To gain a better understanding of the corresponding physical dynamics (e.g., current pattern and discharge), we deployed an updated current instrument (i.e., an Acoustic Doppler Current Profiler, ADCP), which is accepted world ･ wide for its accuracy and high resolution as well as for its ability to resolve the spatial and temporal variations of currents. Using the ADCP, we measured discharges of the dominant inflows and current patterns of a submerged macrophytic area near the shore together with an outflowing area (nearby Kamaguchi floodgate). Our results show that (1) the discharges observed in the dominant inflows (the Kami, Miya and To rivers) are different from those reported by Nagano Prefecture, whereas the outflowing discharge at Kamaguchi Floodgate is similar to that in the Nagano Prefecture report, and (2) the vertical distributions of velocity outside the submerged macrophytic area differ from those inside the area, whose horizontal velocities were reduced by macrophyte-induced turbulence, and (3) the current patterns near the outflow showed a strong velocity in the northeast, rather than in the southwest region.