Provided is an alloy comprising eight or more types of constituent elements, wherein the relative difference in terms of distance between nearest neighbors DNN between a constituent element having the largest distance between nearest neighbors DNN when constituting a bulk crystal from a single element and a constituent element having the smallest distance between nearest neighbors DNN when constituting a bulk crystal from a single element is 9% or less, the number of constituent elements having the same crystal structure when constituting a bulk crystal from a single element is not more than 3, and the difference in concentration between the constituent element having the highest concentration and the constituent element having the lowest concentration is 2 at. % or lower.