We present a brief description of the status of our accelerator mass spectrometry system at the tandem accelerator facility of the University of Tokyo and some examples of measurements in environmental samples which have been recently performed. Fallout10Be activities have been measured, from rain samples collected monthly in Tokyo from 1975 to 1977 and from 1984 to 1986, and compared with those of7Be and137Cs. A preliminary experiment on14C measurement in volcanic gas samples is also reported.