Method and apparatus for determining a particle criterion and particle analyzer using the criterion

A device for determining a particle criterion to set a judgement region as the particle criterion in a distribution data of particles of a specimen to be analyzed and to analyze the particles of the specimen based on particles which appear in the judgement region, comprising:

• first storage means for storing each distribution data of a first specimen group which belongs to a first category;
• second storage means for storing each distribution data of a second specimen group which belongs to a second category;
• first data preparation means for preparing a first fundamental distribution data by accumulating each distribution data of the first specimen group;
• second data preparation means for preparing second fundamental distribution data by accumulating each distribution data of the second specimen group;
• and
• region determining means for determining, as the particle criterion for the specimen to be analyzed, a region on the distribution data where peculiar particles exist in the first or second category by comparing the first fundamental distribution data with the second fundamental distribution data.