A method of driving a pump in a pressure-applying apparatus (10; 12) used to stir a sample diluted with a dilution liquid (LA) prior to the diluted sample being filled into a capillary formed in an analysis tool , the pump including: a flow passage ; a pump configured to impart pressure into the flow passage ; an opening and closing valve that is disposed in the flow passage , and that is configured to open and close the flow passage ; a pressure detector configured to detect pressure in the flow passage ; and an atmospheric air open valve that is disposed in the flow passage , and that is configured to open an interior of the flow passage to atmospheric air, and the method comprising: closing the opening and closing valve and opening the atmospheric air open valve, and then driving the pump ; closing the atmospheric air open valve while continuing to drive the pump ; measuring a pressure in the flow passage by the pressure detector more than once; estimating a time at which an increase in the pressure in the flow passage started based on a change of measurement value with respect to time, wherein the time between the time of closing the atmospheric air open valve and a time of starting an increase in the pressure in the flow passage is a time lag Δt; and evaluating a state of the pump , based on: the pressure detected by the pressure detector at a time at which, after closing the atmospheric air open valve , the time lag Δt has elapsed and then a predetermined time period t1 has elapsed while continuing to drive the pump . a flow passage ; a pump configured to impart pressure into the flow passage ; an opening and closing valve that is disposed in the flow passage , and that is configured to open and close the flow passage ; a pressure detector configured to detect pressure in the flow passage ; and an atmospheric air open valve that is disposed in the flow passage , and that is configured to open an interior of the flow passage to atmospheric air, and the method comprising: closing the opening and closing valve and opening the atmospheric air open valve, and then driving the pump ; closing the atmospheric air open valve while continuing to drive the pump ; measuring a pressure in the flow passage by the pressure detector more than once; estimating a time at which an increase in the pressure in the flow passage started based on a change of measurement value with respect to time, wherein the time between the time of closing the atmospheric air open valve and a time of starting an increase in the pressure in the flow passage is a time lag Δt; and evaluating a state of the pump , based on: the pressure detected by the pressure detector at a time at which, after closing the atmospheric air open valve , the time lag Δt has elapsed and then a predetermined time period t1 has elapsed while continuing to drive the pump . closing the opening and closing valve and opening the atmospheric air open valve, and then driving the pump ; closing the atmospheric air open valve while continuing to drive the pump ; measuring a pressure in the flow passage by the pressure detector more than once; estimating a time at which an increase in the pressure in the flow passage started based on a change of measurement value with respect to time, wherein the time between the time of closing the atmospheric air open valve and a time of starting an increase in the pressure in the flow passage is a time lag Δt; and evaluating a state of the pump , based on: the pressure detected by the pressure detector at a time at which, after closing the atmospheric air open valve , the time lag Δt has elapsed and then a predetermined time period t1 has elapsed while continuing to drive the pump . <EOS>