An experimental study was made on the subjects doing VDT work. The main task is the retrieval and addition of randomized one digit numbers from 3 to 9 under work shift of 60 minutes work with 15 minutes rest. The following three experimental conditions were chosen as the rest conditions ; 1) full rest with the eyes completely closed all through the rest period of 15 minutes, 2) a 5 minutes' physical load by harvard step test was inserted during the 15 minutes rest, and 3) 10 minutes' mental load where the subjects must divide various figures into decided patterns according to the certain rules. From the results, it was clearly be said that the rest taken by the subjects with their eyes closed was a negative countermeasure which could not reduce the VDT fatigue, while physical task could give positive effects on improving the both psycho-physiological conditions. Mental load also gave a positive effect on VDT workers.