1. A management apparatus for managing one or more information processing devices, comprising: a secondary storage storing one or more predefined rules in which a combination of events generated in the information processing devices is taken as a condition and a matter prescribed for the event combination is taken as an inferential conclusion; a network interface which, when an event is generated in the information processing device, receives an event notification corresponding to the content of the event that is transmitted from the information processing device; a processor which determines the status of the information processing device on the basis of the event notification and the corresponding rule; and a memory that is used as a working memory of the processor; wherein the processor: divides the one or more predefined rules into one or more rule segments that comprise a condition and a conclusion that each form part of the rule, and stores the rule segments obtained through the division in the secondary storage, and when an event notification from the information processing device is received, selects one or more related rule segments and, by linking the selected one or more rule segments in the memory as required, constructs a rule parsing network that indicates relationships between rules in the memory, derives an inference on the basis of the constructed rule parsing network, and deletes rule segments that are not readily used in inference derivation from the memory.