A device capable of automatically inspecting and diagnosing an inspection location when an abnormal situation occurs to a gas turbine combustor. In an example embodiment, an inspecting and diagnosing device capable of inspecting and diagnosing inspection locations of a plurality of combustors provided in a gas turbine, the inspecting and diagnosing device calculates as result values function values for unit devices of a power generation facility using a combustion gas flow location temperature index (X), an average combustion gas flow temperature index (Y), a gas turbine swirl angle index (Z), and a gas turbine power output index (MW).