An operation information analyzer (10, 10B, 10C), comprising: an information collection unit (11, 11B) configured to collect event information on events that have occurred during operation of an apparatus including a plurality of devices and to collect process amounts of the apparatus, each process amount being a parameter indicating a measured output of the apparatus, the operation information analyzer characterised in that it further comprises: an information analysis unit (12B, 12C) configured to organize the collected event information to generate and store a first database holding index values used to evaluate operation conditions of the apparatus and a second database in which the event information and behavior of the process amount related to the event information are associated with each other; and an information presentation unit (13, 13B) configured to present the databases (Y, Y2) and the data stored in the information analysis unit (12B, 12C) to a user, wherein the event information includes information on a warning of the apparatus, information on a manipulation of the devices, information on an operation state of the devices, and information on a warning of the operation information analyzer (10, 10B, 10C), the information analysis unit (12B, 12C) is configured to classify the event information into types of the event information either for one or more periods that can be freely selected by the user or for one or more periods selected based on a change in an operation state of the apparatus, so as to generate the first database and the second database, the information presentation unit (13, 13B) is configured to present the first database classified into types of the event information for each period sectioned based on the change in the operation state of the apparatus to the user, and the information analysis unit (12B, 12C) is configured to select, as the process amounts, process amounts whose behavior has changed in a predetermined period before and after the occurrence time of a corresponding event among the process amounts acquired from the information collection unit. an information collection unit (11, 11B) configured to collect event information on events that have occurred during operation of an apparatus including a plurality of devices and to collect process amounts of the apparatus, each process amount being a parameter indicating a measured output of the apparatus, the operation information analyzer characterised in that it further comprises: an information analysis unit (12B, 12C) configured to organize the collected event information to generate and store a first database holding index values used to evaluate operation conditions of the apparatus and a second database in which the event information and behavior of the process amount related to the event information are associated with each other; and an information presentation unit (13, 13B) configured to present the databases (Y, Y2) and the data stored in the information analysis unit (12B, 12C) to a user, wherein the event information includes information on a warning of the apparatus, information on a manipulation of the devices, information on an operation state of the devices, and information on a warning of the operation information analyzer (10, 10B, 10C), the information analysis unit (12B, 12C) is configured to classify the event information into types of the event information either for one or more periods that can be freely selected by the user or for one or more periods selected based on a change in an operation state of the apparatus, so as to generate the first database and the second database, the information presentation unit (13, 13B) is configured to present the first database classified into types of the event information for each period sectioned based on the change in the operation state of the apparatus to the user, and the information analysis unit (12B, 12C) is configured to select, as the process amounts, process amounts whose behavior has changed in a predetermined period before and after the occurrence time of a corresponding event among the process amounts acquired from the information collection unit.