PURPOSE: To surely measure the shapes of fine particles by specifically disposing a plurality of photodetectors.

CONSTITUTION: A sample nozzle 7 is disposed on the Y axis and a photodetector 20 is disposed on the Y axis via a 45° mirror 16, a scattering light condensing lens 17, a scattering slit 18 and a scattering lens 19, with respect to the irradiation system which is provided with a light source lamp 1, an irradiating light condensing lens 2, an irradiating slit 3 and an irradiating lens 4 and of which the optical axis is the Z axis centering at the detecting region D. A photodetector 9 is disposed on the X axis via a light shading disk 11, a scattering light condensing lens 12, a scattering slit 13 and a scattering lens 14. The scattering rays 10, 15 from the microparticles in the detecting region D irradiated with irradiation light 5 are detected with the photodetectors 9, 20 and the scattering intensities having been detected with the photodetectors 9, 20 are contrasted with the scattering intensities of the spherical particles having beforehand been determined, whereby the sizes and shapes of the microparticles are determined. This makes possible checking of the shapes of the particles by a projection method.