PURPOSE: To exactly and efficiently inspect blood by inputting the data from a blood cell counter to an analyzing apparatus and deciding that an increase in eosinophile leukocytes is suspected by specific decision conditions.

CONSTITUTION: The blood cell counter 1 dilutes and hemolyzes the blood, reduces the red blood cells and platelets, determines a white blood cell grain size distribution from a white blood cell sample, and inputs the same to the analyzing apparatus 2. The apparatus 2 sets the boundaries between the middle- size particles and large-size particles in the grain size distribution and designates the size of the particles and the number of the particles in the boundaries as XT2, YT2 respectively. The apparatus sets a, b as constants and decides that the increase in the eosinophile leukocytes is suspected in the case of equation I. The blood inspection is exactly and efficiently executed in this way without depending on inspector's skill.