Abstract
In an urban area the shoppers by car tend to go to suburban shopping centers year by year. So the commercial groups in the downtown shopping district begin to think the shoppers by bicycle important. It is necessary for providing with the bicycle parking spaces to know the extent of sphere area where the shoppers by bicycle come out. Authors calculated the boundary of downtown shopping district's sphere in Kumamoto City by using the modified Huff's model, and verified that most of housewives by bicycle gather from inside of the boundary. This result shows that the modified Huff's model can be applied to the case of limiting the shopper's access mode to bicycle.