This is the book of inverse location theory. Here, the prespecified facilities are given and we want to change the parameters at minimum total cost such that those facilities becomes optimal. My research focuses on two topics. First, I will extend some existing results of inverse location problem to the wider classes of graphs. On the other hand, I will consider the inverse location problem with the ordered median function, a generalization for some objective functions such as median or center function. This book is also fulfilled by the survey of previous works on the topic and future possible research directions.