1. A job management device, comprising: a memory; and one or more processors coupled to the memory and configured to: acquire a ratio that indicates at least one of a first ratio of a number of vertices, that correspond to computing resources to which a job is not assigned and that are adjacent to a subgraph included in a graph including a plurality of vertices indicating computing resources of a computer system, and a plurality of edges indicating links between the computing resources to a number of vertices belonging to the subgraph for computing resources to which a certain job is assigned, a second ratio of a number of vertices that are adjacent to a plurality of vertices belonging to the subgraph and that correspond to computing resources to which a job is not assigned to the number of the vertices belonging to the subgraph, a third ratio of a number of vertices that belong to the subgraph and are adjacent to the plurality of vertices corresponding to computing resources to which a job is not assigned and that are adjacent to the subgraph to the number of the vertices belonging to the subgraph, a fourth ratio of a number of edges that are located between vertices belonging to the subgraph and vertices adjacent to the subgraph and corresponding to computing resources to which a job is not assigned to the number of the vertices belonging the subgraph, and a fifth ratio of a number of the edges that are located between the vertices belonging to the subgraph and the vertices adjacent to the subgraph and corresponding to the computing resources to which a job is not assigned to the number of edges between the vertices belonging to the subgraph; calculate, based on the ratio, an index value related to a load to be applied due to a search, to be performed, of a computing resource to which another job is to be assigned; determine, based on the index value, a number of processing elements in order to perform the search of the computing resource to which the another job is to be assigned; control the number of processing elements to perform the search of the computing resource using the subgraph as an evaluation standard for the search; and assign, based on results of the search, the another job to the computing resource.