The present invention is a reagent preparation apparatus, comprising: a reagent preparation unit configured to prepare a reagent for processing a sample; a measuring unit configured to measure a property of the reagent prepared by the reagent preparation unit; a waste section configured to discard the prepared reagent when a measurement result by the measuring unit does not meet a predetermined condition; and a controller configured to control a reagent preparation operation of the reagent preparation unit, wherein the controller controls the reagent preparation unit to stop the reagent preparation operation when a number of times of discarding a reagent has reached a predetermined plurality of times.