Usefulness of biometric information obtained from biosensor worn by employees for assessing organization environment in workplace was investigated. In 85 employees, heart rate variability (HRV) indices calculated from the time series of R-R intervals of electrocardiogram during work hours were compared with the responses to a questionnaire concerning job stress, communication, and physical and mental conditions and HRV indices were also compared between before and after intervention for improving workplace organization. The higher the arbitrariness in work, the smaller the SD of R-R interval and the very low frequency (VLF) and low frequency (LF) amplitude of HRV, the higher the mental frustration and fatigue, the worse the communication with the boss and colleagues, the greater the LF amplitude and SD of LF amplitude (LFsd). By factor analysis of the responses to questionnaire, three factors reflecting stress, depressiveness, and fatigue were extracted. Among the factors extracted, the LF amplitude and LFsd correlated with the degree of fatigue. The intervention activities decreased LF amplitude and LFsd among subjects who reported to have deeply participated in the activities, while these indices increased among those reported to have not participated much.