1. A job managing device, comprising: a memory; and one more processors coupled to the memory and configured to execute: a process of managing data on a first subgraph that is 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 and is provided for a first computing resource to which one or more first jobs are assigned, or data on a second subgraph that is included in the graph and connected to the first subgraph through a vertex indicating a computing resource to which none of the one or more first jobs is assigned in the graph and that is provided for a second computing resource to which a second job is assigned, and a process of using the data to determine, based on the first subgraph, whether a third computing resource to which a third job is to be assigned exists.