To provide a particle image analyzer capable of obtaining the morphological feature data of particles from the phase difference image of imaged particles.

The particle image analyzer includes an irradiation part 30 for illuminating particles, an imaging part 80 for imaging the illuminated particles to acquire a phase difference image, an image processing substrate 6 for extracting a particle image from the acquired phase difference image and analyzing the extracted particle image to calculate the morphological feature data showing the morphological feature of the particles and an image data processing part 2b. Further, the image processing substrate 6 and the image data processing part 2b extract a particle image from the phase difference image on the basis of a binary threshold value smaller than the brightness value substantially corresponding to the background of the particle image and the binary threshold value larger than the brightness value substantially corresponding to the background of the particle image.