To easily crush even an object substance having a relatively high water content to be crushed.

A drive side crushing drum 3 and an induction side crushing drum 4 are adjacently arranged while respective rotation axes being set parallel. Respective crushing grooves 26, 28 are spirally formed in the outer circumferences of the drive side crushing drum 3 and the induction side crushing drum 4 in the same direction. An object substance to be crushed is supplied between the drive side crushing drum 3 and the induction side crushing drum 4 and then the drive side crushing drum 3 and the induction side crushing drum 4 are rotated in mutually opposed directions.