A medical diagnosis support apparatus which provides information, for a target case, to be checked by a diagnosis user, said apparatus comprising: first obtaining means for obtaining already input information (Ef), which has already been input, indicating medical information input from an input unit with respect to respective items (Ij) of the medical information for the target case; second obtaining means for obtaining non-input information (Evm), which has not been input yet, indicating medical information which can be input about an item (Nf') different from an item (Nf) input as the already input information (Ef) among the respective items (Ij) of the medical information for the target case, wherein the second obtaining means is configured to obtain, as the non-input information (Evm), at least one piece of information obtained by subtracting the already input information (Ef) from all the items (Ij) of medical information which can be input and are obtained from a database; probability calculation means for calculating an occurrence probability Pc(Evm) by using the total number of cases and a co-occurrence frequency which is a frequency of a case including both each non-input information (Evm) and the already input information (Ef), based on information of diagnosis results stored in a past in the database; inferring means for executing a first inference for inferring a diagnosis name (Dr) based on the already input information (Ef) and a second inference for inferring a diagnosis name (Dr) based on respective sets obtained by pairing the already input information (Ef) and each non-input information (Evm), and obtaining diagnosis names (Dr) from the first inference and the second inference, and obtaining an inference probability P(Dr|E) indicating that the target case is each diagnosis name; influence degree calculation means for calculating an influence degree IR(Evm) of each non-input information on the second inference based on an inference probability obtained from the first inference and an inference probability obtained from the second inference, wherein IR(Evm) is the degree of variation in inference probability of each diagnosis name upon addition of the non-input information; and selection means for selecting, as information to be presented, at least one piece of the non-input information based on the occurrence probability of each non-input information and the influence degree of each non-input information, by obtaining an evaluation value W(Evm) of each non-input information (Evm) as the product of the occurrence probability Pc(Evm) and the influence degree IR(Evm) of the non-input information, and selecting the piece of the non-input information which gives the maximum value W(Evm) as the information to be presented. first obtaining means for obtaining already input information (Ef), which has already been input, indicating medical information input from an input unit with respect to respective items (Ij) of the medical information for the target case; second obtaining means for obtaining non-input information (Evm), which has not been input yet, indicating medical information which can be input about an item (Nf') different from an item (Nf) input as the already input information (Ef) among the respective items (Ij) of the medical information for the target case, wherein the second obtaining means is configured to obtain, as the non-input information (Evm), at least one piece of information obtained by subtracting the already input information (Ef) from all the items (Ij) of medical information which can be input and are obtained from a database; probability calculation means for calculating an occurrence probability Pc(Evm) by using the total number of cases and a co-occurrence frequency which is a frequency of a case including both each non-input information (Evm) and the already input information (Ef), based on information of diagnosis results stored in a past in the database; inferring means for executing a first inference for inferring a diagnosis name (Dr) based on the already input information (Ef) and a second inference for inferring a diagnosis name (Dr) based on respective sets obtained by pairing the already input information (Ef) and each non-input information (Evm), and obtaining diagnosis names (Dr) from the first inference and the second inference, and obtaining an inference probability P(Dr|E) indicating that the target case is each diagnosis name; influence degree calculation means for calculating an influence degree IR(Evm) of each non-input information on the second inference based on an inference probability obtained from the first inference and an inference probability obtained from the second inference, wherein IR(Evm) is the degree of variation in inference probability of each diagnosis name upon addition of the non-input information; and selection means for selecting, as information to be presented, at least one piece of the non-input information based on the occurrence probability of each non-input information and the influence degree of each non-input information, by obtaining an evaluation value W(Evm) of each non-input information (Evm) as the product of the occurrence probability Pc(Evm) and the influence degree IR(Evm) of the non-input information, and selecting the piece of the non-input information which gives the maximum value W(Evm) as the information to be presented.