An air conditioning system diagnosis apparatus comprising: communication means (30, 110) for, in an air conditioning system in which a plurality of devices are connected by a network and the related devices transmit and receive a control signal to and from each other over the network, performing communication between the devices over the network; device type identifying means for identifying a device type that indicates a type of each device; communication list generating means for generating a communication list that includes a combination of the devices being a communication source and a communication destination of the control signal; and system diagnosis means for performing a diagnosis on the air conditioning system using information acquired through the communication means (30, 110) and deriving a diagnosis result; characterized by: system structure analyzing means for deriving system structure information that indicates a device configuration of the air conditioning system from the device type and the communication list; diagnosis result superimposed diagram generating means for generating a system structure diagram on the basis of the system structure information acquired from the system structure analyzing means and superimposing an highlighted content of the diagnosis result in the system structure diagram; and a display unit that is adapted to acquire the system structure diagram in which the content of the diagnosis result is superimposed from the diagnosis result superimposed diagram generating means and to display the system structure diagram, wherein the plurality of devices include an outdoor unit and an indoor unit forming a refrigeration cycle, and if a failure of the refrigeration cycle is found in a refrigeration cycle diagnosis result by the system diagnosis means, the system structure diagram in which the outdoor unit, the indoor unit, and a connection line between the outdoor unit and the indoor unit are highlighted is generated by the diagnosis result superimposed diagram generating means. communication means (30, 110) for, in an air conditioning system in which a plurality of devices are connected by a network and the related devices transmit and receive a control signal to and from each other over the network, performing communication between the devices over the network; device type identifying means for identifying a device type that indicates a type of each device; communication list generating means for generating a communication list that includes a combination of the devices being a communication source and a communication destination of the control signal; and system diagnosis means for performing a diagnosis on the air conditioning system using information acquired through the communication means (30, 110) and deriving a diagnosis result; characterized by: system structure analyzing means for deriving system structure information that indicates a device configuration of the air conditioning system from the device type and the communication list; diagnosis result superimposed diagram generating means for generating a system structure diagram on the basis of the system structure information acquired from the system structure analyzing means and superimposing an highlighted content of the diagnosis result in the system structure diagram; and a display unit that is adapted to acquire the system structure diagram in which the content of the diagnosis result is superimposed from the diagnosis result superimposed diagram generating means and to display the system structure diagram, wherein the plurality of devices include an outdoor unit and an indoor unit forming a refrigeration cycle, and if a failure of the refrigeration cycle is found in a refrigeration cycle diagnosis result by the system diagnosis means, the system structure diagram in which the outdoor unit, the indoor unit, and a connection line between the outdoor unit and the indoor unit are highlighted is generated by the diagnosis result superimposed diagram generating means. system structure analyzing means for deriving system structure information that indicates a device configuration of the air conditioning system from the device type and the communication list; diagnosis result superimposed diagram generating means for generating a system structure diagram on the basis of the system structure information acquired from the system structure analyzing means and superimposing an highlighted content of the diagnosis result in the system structure diagram; and a display unit that is adapted to acquire the system structure diagram in which the content of the diagnosis result is superimposed from the diagnosis result superimposed diagram generating means and to display the system structure diagram, wherein the plurality of devices include an outdoor unit and an indoor unit forming a refrigeration cycle, and if a failure of the refrigeration cycle is found in a refrigeration cycle diagnosis result by the system diagnosis means, the system structure diagram in which the outdoor unit, the indoor unit, and a connection line between the outdoor unit and the indoor unit are highlighted is generated by the diagnosis result superimposed diagram generating means.