When automatically classified results are different from judgment of a laboratory technician, the laboratory technician has to reselect the bacterial colonies one-by-one to be a pickup colony through watching the displayed image. To get rid of the inconvenience, provided is a pretreatment device for a bacteria test comprising: a specification unit by which an operator instructs to specify the number of bacterial colonies and the increased/decreased number of the bacterial colonies to be displayed; and a display unit for displaying classification results obtained following the operator's instruction. The pretreatment device for a bacteria test facilitates the automatically classified results to be brought close to the judgment of the laboratory technician, resulting in the saving of the time required for checking the appropriate bacterial colonies for the pickup colony.