To change a flow rate with a high accuracy in a pump for a medical application.

When a mode is turned to a calibration mode, each point within all ranges in a pump driving value (voltage and the like) corresponding to a variable flow rate range is applied on a pump driving means 14 in order, a pump flow rate in each driving value is measured by a flow rate measuring means 21, those driving value and a flow rate are set to a flow rate characteristic table 11, a driving value is decided from the flow rate characteristic table 11 according to the set flow rate at the time of normal use, and then a pump is driven. A fluid used when the flow rate of the flow rate measuring means 21 is measured is circulated from a tank 27 to a pump main body 15.