With the aging of Japanese population, various welfare equipment such as rehabilitation apparatus have been developed widely to prevent deterioration of the disease and to recover the health. It is desired to develop the suitable equipment for each human having different character and condition, since many of them are mass-produced and general-purpose tools. Then the new rehabilitation machines, which control the power in accordance with the user condition by introducing a biological monitor and feedback system of the signal, is proposed as safety and pleasant training tool. Here the basic research was carried out for such idea by using rehabilitation training machine “leg press” with the aim of strengthening antigravity muscles of the leg by the training. Biological signal and information during the machine training were measured for younger generation as well as elder person, and the relation between muscle force suffered from the external load and comfortableness as an internal reaction of the body was examined. Here the content of α wave from the pattern of electrical brain waves in electroencephalography (EEG), and skin temperature of the face were measured for the evaluation of comfortableness, while electromyography (EMG) is used to measure the muscle strength.