This experiment was conducted to evaluate individual difference of chewing speed and chews per bolus duing the rumination using twenty three heads of grazing cattle and thirty six heads of barn feeding cattle. Rumination behaviour was measured and recorded by the masster EMC telemeter and visual observation. The chewing speed (chews/lOOsec) was significantly different individually (C.V. 13.0-14.5 %) among the variable aged group (1-60 months), but that of same aged group showed lower difference (C.V. 4.5 %). The chews per bolus showed even larger individually difference than the chewing speed, so the variable aged group (1-60 months) resulted the 15.5-16.2 %of C.V.and the same aged group showed the 9.5 % of C.V. Under 12 month aged cattle showed more rapid chewing speed than older aged cattle. The chewing speed changed with the growth of cattle, but the chews per bolus did not show any relationship with age, so it is regarded as the individually characteristic pattern.