PURPOSE: To simultaneously measure both the content of solid particles and the particle size thereof by calculating them from the relation between the ratio of the content of the liquid and the specific surface area obtained through measurement of the permeating velocity of the liquid of solid fat products.

CONSTITUTION: Two kinds of the permeating velocity of a liquid substance of a solid-liquid disperse system are measured for an area where the disperse system acts as an elastic system and for an area where the disperse system represents no elasticity. The content (volume ratio) of a liquid and the specific surface area are calculated from the relation therebetween obtained by measuring the permeating velocity of the liquid substance of solid fat products. Accordingly, the content of solid particle and particle size thereof can be measured simultaneously.