To enhance separability of a cleaved piece while durability of a cleaving edged tool is made excellent by a method wherein one stage of a cleaving process is divided into two process stages, and in the second stage the cleaved piece passed through the first stage is passed through a group of edged tools arranged at a pitch almost equal to a pitch in a pair of rotary cutting tools at the first stage.

As a group of edged tools at a first stage a plurality pairs of rotary double-edged tools opposed vertically to each other, are arranged parallel to each other. Just thereafter, as a group of edged tools at the second stage, a plurality of fixed plain edged tools are arranged parallel to each other at the same pitch as a pitch between respective rotary edged tools at the first stage. After passing raw material wood 3 through the group of edged tools at a first stage of a small cant process, wood fiber remaining uncut at the first stage is cut to a small cant cleaved piece 4 by passing through the group of edged tools at the second stage.