This study aims to forecast what amount of economic effects the new Fukuoka City Subway Line 3 would induce on city center retail sector. The new Subway Line 3 connects the southwest part of suburban residential area to the city center retail district of Fukuoka. If residents in this area change their travel mode from bus to subway, they drastically can reduce their travel time to the city center from the present 40 or 50 minutes to the coming 20 minutes. The improvement of accessibility would increase their frequency of visits to the city center. We regard this phenomenon as the increase of travel demand to city center since for the residents along Subway Line 3, the relative price of city center goods declines as the generalized travel cost falls. Since the residents increase their frequency of visits, the number of visitors at the city center increases. Thus the turnover of city center retail sector must increase. This increase of turnover was estimated, regarded as the economic effects on city center retail sector induced by the new subway line. We call the above procedure as consumer behavior approach because all the estimation processes hinge on the predictive behavioral changes of consumers after the new subway line, i.e., policy is introduced. To estimate the economic effect, most of traditional transport studies have relied on the user benefits accrued to the decrease of travel time caused by the introduction of new railway. While those previous studies are appropriate for estimating the net economic benefits it must not be so for our present purpose to estimate the economic effects on the retail sector at the restricted area such as city center. Based on the above consumer behavioral approach, first we constructed two models: modal change and visit frequency models. Parameters of these two models are estimated from data obtained from the survey about consumer travel behavior that was conducted at the city center for respondents sampled from visitors there. We delineate the border of the residential tract whose inhabitants have the possibility to use the new subway line. The resulted tract contains divisions of 278 residential addresses. Using these two estimated models we forecast modal choice, frequency of visits to the city center, and expenditure at the city center by residents for each of 278 residential divisions and then sum them up. As a result, the amount of economic effects of the new subway line on the city center retail sector of Fukuoka City turns out to be 17.7 billion yen per year. JEL Classification: D12, R41