Measured blood pressure data is stored in a memory in association with information related to a measurement time. In response to manipulation of a manipulation portion (memory recall switch), blood pressure data associated with the measurement time within a prescribed time period (for example, 10 minutes) from the measurement time of reference blood pressure data, among the blood pressure data stored in the memory, is retrieved as specific data. Then, an average value is calculated based on the specific data, and the calculated average value is displayed as an evaluation index.