A similar case search apparatus adapted to search for a similar case including a case image similar to a target image which is a medical examination target from a plurality of cases including the case image, comprising: a first type acquisition unit adapted to acquire a type of target lesion which is a lesion present in the target image; a second type acquisition unit adapted to acquire a type of case lesion which is a lesion present in a case image; a first feature amount acquisition unit adapted to acquire a feature amount of the target lesion; a second feature amount acquisition unit adapted to acquire a feature amount of the case lesion; an individual lesion similarity calculation unit adapted to calculate an individual lesion similarity which is a similarity between the target lesion and the case lesion of the same type on the basis of the feature amount of the target lesion and the feature amount of the case lesion; a weighting processing unit adapted to perform a weighting process for the individual lesion similarity, using weighting coefficients which are preset for each of a plurality of types and a plurality of purposes, wherein the purposes include a purpose of specifying a disease name and a purpose of specifying a severity of a disease, and to perform the weighting process, using a first weighting coefficient which is the weighting coefficient corresponding to a degree of contribution of each type to the specification of the disease name, and to perform the weighting process, using a second weighting coefficient which is the weighting coefficient corresponding to a degree of contribution of each type to the specification of the severity, a total similarity calculation unit adapted to calculate a total similarity between the target image and the case image for each of the purposes on the basis of the individual lesion similarity subjected to the weighting process; and a search unit adapted to search for the similar case on the basis of the total similarities. a first type acquisition unit adapted to acquire a type of target lesion which is a lesion present in the target image; a second type acquisition unit adapted to acquire a type of case lesion which is a lesion present in a case image; a first feature amount acquisition unit adapted to acquire a feature amount of the target lesion; a second feature amount acquisition unit adapted to acquire a feature amount of the case lesion; an individual lesion similarity calculation unit adapted to calculate an individual lesion similarity which is a similarity between the target lesion and the case lesion of the same type on the basis of the feature amount of the target lesion and the feature amount of the case lesion; a weighting processing unit adapted to perform a weighting process for the individual lesion similarity, using weighting coefficients which are preset for each of a plurality of types and a plurality of purposes, wherein the purposes include a purpose of specifying a disease name and a purpose of specifying a severity of a disease, and to perform the weighting process, using a first weighting coefficient which is the weighting coefficient corresponding to a degree of contribution of each type to the specification of the disease name, and to perform the weighting process, using a second weighting coefficient which is the weighting coefficient corresponding to a degree of contribution of each type to the specification of the severity, a total similarity calculation unit adapted to calculate a total similarity between the target image and the case image for each of the purposes on the basis of the individual lesion similarity subjected to the weighting process; and a search unit adapted to search for the similar case on the basis of the total similarities.