Abstract : Dénes Kőnig is known as a mathematician with his important works on graph theory. Before starting professional works, in 1902 and 1905 when he was a student, he successively published two books on mathematical recreations in Hungarian, but these books are not yet much examined by historians. In the present dissertation, I translated these books into English, and compared the contents with Kőnig's treatise on graph theory in 1936. I found that many problems treated in the second book on mathematical recreations in 1905 were treated again in the treatise of 1936, and that many problems treated in the treatise of 1936 were already treated in the second book on mathematical recreations in 1905. In these two publications, same problems were treated in different ways. To clarify the relation between mathematical recreations and graph theory, I analyzed how some features of the diagrams of graph theory and some concepts of it took shape in the context of mathematical recreations. I found that Tarry, in his talk on geometry of situation in a conference in 1886, integrated some concepts of different topics of mathematical recreations, and that he used the same type of diagrams for considering problems in different topics. The elements of Tarry's diagrams are similar to those used in Kőnig's treatise of 1936, and the corresponding concepts can be considered as one of the representations of the concepts of graph theory defined in Kőnig's treatise of 1936.