In order to evaluate masticatory efficiency easily, the method of appreciation of chewing ability was determined applying the particle analyzer by TV measuring system (PLAMSYSTEM). Ten subjects with normal dentition were tested. The test food was two grams weight of peanut. After 10 masticatory strokes, the crushed particles remaining on 10 mesh sieve were measured. The sieve-analysis represented particles as the equivalent of sphere, therefore, in this study, particle size distribution was analyzed by the equivalent of diameter.1. The particle size distribution showed a peak at 2-2.5mm diameter. In a part of large particles, the number of particles exhibited rapid decrease, and the particles above 4mm were few.2. In the particle weight distribution obtained by calculating from the size distribution, the chewing ability were divided into three patterns according to the difference of the distribution in a part of large particles.3. With increase of masticatory strokes, large particles were crushed selectively.4. The ability of food crushing was observed clearly in the particle weight distribution, especially in the part of large particles.