In a liquid stirring method, after a second liquid is discharged into a reaction container accommodating a first liquid from a dispensing probe provided with a dispensing tip at the leading end thereof, a mixture of the first liquid and second liquid in the container is stirred by being sucked out and discharged by the dispensing probe. The number of stirrings through sucking out and discharging is changed according to the total volume of the first liquid and second liquid. If the total volume of the first liquid and second liquid is below a preset threshold, sucking out and discharging is repeated for a prescribed number of times.