1. A method for measuring bacteria comprising: fluorescently staining bacteria in a sample; detecting size information from the bacteria in the sample, and fluorescence information expressing intensity of fluorescent light emitted by the bacteria; creating a scattergram representing a distribution of the bacteria based on the size information and the fluorescence information detected; analyzing the distribution of the bacteria in the scattergram; and determining whether the bacteria in the sample is bacillus or coccus based on a result of the analyzing.