A medical information processing device, comprising: a dosage details acquisition unit configured to acquire a plurality of dosage details in which information specifying a drug administered to a subject patient, an amount of the drug, and a dosing date of the drug are associated with each other; and a stable dosing period determination unit configured to identify a dosing period equal to or longer than a predetermined period according to a target disease and a determination purpose, among dosing periods of the drug for which it is regarded that both the information specifying the drug and the amount of the drug are the same, based on the plurality of acquired dosage details, to specify the identified dosing period as a dosage details common period, and to determine a period excluding a predetermined initial or final period from the specified dosage details common period as a stable dosing period; a medical information acquisition unit configured to acquire medical information including an item of inspections performed on the subject patient, inspection data of the subject patient corresponding to each inspection item, and an inspection time of the inspection data; and a feature amount analysis unit configured to extract the medical information corresponding to the inspection item that is performed at the inspection time during the stable dosing period, from the acquired medical information, as specific medical information and to acquire a feature amount from specific inspection data that is the inspection data corresponding to the extracted specific medical information, wherein the feature amount analysis unit further includes a determination section configured to acquire a determination time of the subject patient, and to determine presence or absence of an abnormality with respect to the determination purpose of the target disease at the determination time according to determination conditions corresponding to the determination purpose of the target disease based on the feature amount extracted from the specific inspection data included in the stable dosing period before the determination time. a dosage details acquisition unit configured to acquire a plurality of dosage details in which information specifying a drug administered to a subject patient, an amount of the drug, and a dosing date of the drug are associated with each other; and a stable dosing period determination unit configured to identify a dosing period equal to or longer than a predetermined period according to a target disease and a determination purpose, among dosing periods of the drug for which it is regarded that both the information specifying the drug and the amount of the drug are the same, based on the plurality of acquired dosage details, to specify the identified dosing period as a dosage details common period, and to determine a period excluding a predetermined initial or final period from the specified dosage details common period as a stable dosing period; a medical information acquisition unit configured to acquire medical information including an item of inspections performed on the subject patient, inspection data of the subject patient corresponding to each inspection item, and an inspection time of the inspection data; and a feature amount analysis unit configured to extract the medical information corresponding to the inspection item that is performed at the inspection time during the stable dosing period, from the acquired medical information, as specific medical information and to acquire a feature amount from specific inspection data that is the inspection data corresponding to the extracted specific medical information, wherein the feature amount analysis unit further includes a determination section configured to acquire a determination time of the subject patient, and to determine presence or absence of an abnormality with respect to the determination purpose of the target disease at the determination time according to determination conditions corresponding to the determination purpose of the target disease based on the feature amount extracted from the specific inspection data included in the stable dosing period before the determination time.