Recently a number of patients of allergic diseases, bronchial asthma or allergic rhinitis, is markedly increasing. Some clinical traials and investigations have shown that physical activities may modify these allergic symptoms. Mechanisms of allergic diseases are essentially same as normal immunological response. A research field concerning effects of exercise or training on immunological responses have been highlighted. For clarifying the effects of training to training to prevent allergic disease, Brown Norway (BN) rat was used in this experiment. BN rat has been given attention by was used in this experiment. BN rat has given attention by characters as ahigh responder strain of IgE and an eosinophilia in bronchoalveolar lavage fluid (BALF). Male BN rat (5 weeks) were divided into followin 3 group. 1) Forced group exercise on an treadmill at belt speed of 30 m/min for 30 min/day, 2) Voluntary group housed with running wheels, and 3) Control group housed under sedentary conditions. Body weight and food consuption during the experimental period (6 weeks) showed significant changes. Voluntary group was significantly smaller than Voluntary or Control groups, however, there was no significant difference in body weights between Voluntary and Control groups. Forced and Volutary groups run about 18 km and 114 km during the experimental period, respectively. After 6 weeks of the experiment, the rats were sacrificed at the age of 11 weeks. No significant differences of cell numbers in diameter in diameter 8.0 to 10.0 μm, suggesting eosinophils, in BALF were observed among groups. However, Control group showed higher mean level than Forced and Voluntary groups, 4.26×106, 2.61×106, and 3.61×106 cells, respectively. Furthermore, Control group showed higher cell population in diameter 6.3 to 8.0 μm, suggesting, in BALF than Forced and Voluntary groups without statistical significance. These results suggest that physical activities either forced or voluntary may have preventive effect on allergic diseases and the voluntary exercise is recommended for the physical activities.