One of the characteristics that represent life quality is the indicator of accessibility. Accessibility means the ease of access for a citizen in a determined location, who tends to reach a particular activity in a particular time, using a designated mode of traortation, with an acceptable quality. Accessibility represents how easy a citizen reaches the activity. Increasing accessibility, which can be assessed by indicators such as travel time, can cause negative effects like extra air pollution and additional social costs. In the past, different methods of assessing accessibility were presented, used and developed. In each of these methods, some of the most important factors were considered for assessing the degree of accessibility. In almost all previous methods of assessing accessibility, only the users’ costs were to be considered. However, sustainable accessibility can only be evaluated by considering all of the costs like air pollution, costs of accidents, costs of maintenance, etc. Sustainable accessibility is the kind of accessibility that not only does it make it easy for citizens to reach their activities, but also doesn’t adversely affect the consumption quality of future generations. A new equation will be presented in this research to assess accessibility, which includes social costs and operating costs in addition to user costs that used to be considered in previous assessment methods. To achieve this, Kowsar daily markets of Isfahan were chosen to be studied. Trip generating information of these markets were obtained by conducting a poll on twelve Kowsar markets. By fitting a curve on the collected information, an equation is developed which is compatible with conditions of this city. Accessibility indicator of the markets were calculated in two ways; 1-traditional method of assessing accessibility, and 2-sustainable accessibility assessment method, which is presented in this research for the first time. Results show that sustainable accessibility assessment method can obviously present marginal effects of different modes of traortation, and also in case of considering all costs, sustainable accessibility indicator of private car will be less than other traortation modes. Urban areas with better public traortation services and none-motorized services will have greater accessibility indicator with the related traortation mode. As a result, urban traortation policy-makers should notice that all of the costs of traortation have to be considered to make accurate decisions which is compatible with sustainable traortation