The present invention provides a device for predicting prognosis of a patient who undergoes PEG, which allows a doctor to obtain predictive results sufficient to judge whether or not to perform the PEG (percutaneous endoscopic gastrostomy) for the patient. This device includes: a prognosis prediction expression storage section 14 configured to store a prognosis prediction expression, the prognosis prediction expression being calculated by applying prediction input factors and prediction output factors about a first patient who already underwent the PEG, to ANN (artificial neural network)； and a processing section 16 configured to: receive diagnosis input factors about a second patient, for judging whether or not to perform the PEG on the second patient； calculate diagnosis output factors in response to the diagnosis input factors based on the prognosis prediction expression； and output the calculated diagnosis output factors.
