Nowadays, tourism industry is one of the most important economic sectors in many countries and development of this industry receives priority by many of the governments. Given its natural and comparative advantages, ancient civilization and religious and historic places, Iran is a suitable region for investment in tourism industry. One of the most important factors conducive to the development of this industry is banking credits and loans. This study trying to make a Fuzzy Multiple Attribute Decision Making Model (FMADM), for determination of the economical investment index, priorities and optimum percentages of credits allocated for investment in tourism industry of Iran's provinces. for this purpose, we take a combination of 15 economical indexes and Fuzzy Logic, to account uncertainty conditions and fluctuations in inputs and outputs quantities. This study covers all the Iranian provinces, for the period of (2001-2008). The results show that, the provinces of Tehran, Hormozgan, Mazandaran, Khorasan Razavi, Gilan, Esfahan, Golestan, Ghom, Fars and Yazd maintain the rankings of one to ten, in terms of priorities for investment in tourism industry respectively. Furthermore, given the uncertain conditions and fluctuations in inputs and outputs in this industry, current structure of banking credits and loans, extended to tourism sector, is not optimum and there is the need for adjustments in volumes of banking loans and percentages of credits, allocated to this sector.