On the contrary to the expansion of feasibility studies on public construction and development projects, there is few feasibility studies on S&T, especially large-scale basic research facilities. Based on this critical mind, we tried the first feasibility study on large-scale basic research facilities, that is, the 4th Generation Light Source. First, it is validated whether the construction of 4th Generation Light Source is economically feasible and second, if economically feasible, the optimal place and time for construction are analyzed by using Analytical Hierarchy Process. This research shows that the construction is economically feasible irregardless of scenarios on future bio-medicine industry growth and to construct at Pohang in 2006 is optimal strategy. On the basis of this analysis, the feasibility studies on large-scale basic research facilities are expected to be more expanded and developed.