The task is to provide a system which supports smooth patient referral from a referral source medical institution to a referral destination medical institution and which particularly prevents readmission due to cases that are difficult to determine simply based on patient attributes or due to the quality of medical services. To achieve this task, a referral difficult degree calculation unit calculates a referral difficulty degree which quantifies the risk that a patient cannot be discharged because a referral destination cannot be found, in consideration of a readmission risk calculated by a readmission risk calculation unit, the geographical distance between the patient and the referral destination medical institution, the total number of patients accepted, and the number of beds available. This referral difficulty degree is outputted to an output unit of the referral source medical institution or the referral destination medical institution.