More than ten year ago Seto-Ohashi was constructed, last April Akashi-Kaikyo-Ohashi was completed, and this May Onomichi-Imabari route is going to be provided as the third road connecting Honsyu with Shikoku area. At the end of this century, as a result, Seto-uchi area has three main routes which would improve interregional mobility. Progress of traffic infrastructure could change city's economic position. On one side, some cities may grow by improving interregional accessibility. On the other side, however, some cities may lose their economic status due to so called 'straw effects'. This paper consists of two parts; the former part is focussed on recent regional economic changes and statistical analyses on city position of importance, the latter part is empirical investigation based on the results of questionnaire about city positions of importance. Regional recent changes mean office location and relocation as a firms' regional evaluations. In statistical analyses I propose a new indicator of city's relative economic importance. Questionnaire has been conducted for branch offices of major four cities in Seto-uchi area. Through questionnaire several evaluations of individual cities by corporate firms are clarified.