A diagnosis support apparatus comprising: display control means configured to display an input GUI adapted to receive input of medical information in the form of a plurality of findings regarding a subject; deducing means configured to deduce, for a plurality of diagnoses, a probability of each diagnosis (Dr) of the subject on the basis of the plurality of findings input through the input GUI; a diagnosis setting means configured to set the diagnosis having the highest deduced probability among the plurality of diagnoses as a subject diagnosis; determining means (106, 110, 809) configured to determine contribution ratios (C(Dr|Sjk)) of each of the plurality of input findings to the subject diagnosis, which contribution ratio for each input finding whose contribution is to be determined is a difference between a probability of the subject diagnosis on the basis of all the plurality of input findings and a probability of the subject diagnosis on the basis of all the plurality of findings excluding the input finding whose contribution is to be determined, a contribution ratio of an input finding that affirms the diagnosis having a positive value and a contribution ratio of an input finding that denies the diagnosis having a negative value; and factor selecting means configured to select, based on the calculated contribution ratios, the input finding that has a maximum positive contribution ratio for the subject diagnosis as positive information and the finding that has a maximum negative contribution ratio for the subject diagnosis as negative information, wherein the display control means is configured to change the display form of the input GUI to emphasize the appearance of the input GUI regions which receive input of a finding corresponding to the positive information and a finding corresponding to the negative information. display control means configured to display an input GUI adapted to receive input of medical information in the form of a plurality of findings regarding a subject; deducing means configured to deduce, for a plurality of diagnoses, a probability of each diagnosis (Dr) of the subject on the basis of the plurality of findings input through the input GUI; a diagnosis setting means configured to set the diagnosis having the highest deduced probability among the plurality of diagnoses as a subject diagnosis; determining means (106, 110, 809) configured to determine contribution ratios (C(Dr|Sjk)) of each of the plurality of input findings to the subject diagnosis, which contribution ratio for each input finding whose contribution is to be determined is a difference between a probability of the subject diagnosis on the basis of all the plurality of input findings and a probability of the subject diagnosis on the basis of all the plurality of findings excluding the input finding whose contribution is to be determined, a contribution ratio of an input finding that affirms the diagnosis having a positive value and a contribution ratio of an input finding that denies the diagnosis having a negative value; and factor selecting means configured to select, based on the calculated contribution ratios, the input finding that has a maximum positive contribution ratio for the subject diagnosis as positive information and the finding that has a maximum negative contribution ratio for the subject diagnosis as negative information, wherein the display control means is configured to change the display form of the input GUI to emphasize the appearance of the input GUI regions which receive input of a finding corresponding to the positive information and a finding corresponding to the negative information.