Average blood pressure data of a morning time zone of every week and average blood pressure data of a night time zone of every week calculated by an average calculation portion are stored in a memory by performing blood pressure measurement. An every-week processing portion alternately switches and displays the average blood pressure data of the morning time zone and the average blood pressure data of the night time zone read from the memory based on an instruction input through an operation unit on a display unit every three seconds, or the like.