Operators’ skills have been evaluated visually by a teacher or an in- structor of operators, but it is not possible to know the psychological change of the operator. Authors investigate the method which uses the physiological indices to estimate tension and concentration of the crane operators in different skill levels. Electromyogram (EMG) of the masseter muscle and R-R Interval (RRI) which calculates of heart rate variability (SDNN / RMSSD) are selected. The data were measured in each of the two operation tests of eight operators with different skill levels. As a result, the physiological indices show great reaction to tension and concentration, and the estimation showed that there are charac- teristics in tension and concentration scenes depending on the skill levels.