PURPOSE: To provide a simple device for correction-sawing roughly sawn squared timber.

CONSTITUTION: A pair of centering units 3A, each one of which is movable along the longitudinal direction (which makes an X-axis) of a machine bed and with which a squared timber is respectively gripped at the fixed positions, located inside the timber by about 15% of the total length of the timber from both the ends of the timber so as to coincide the timber with a centering standard axis (which makes an Xa-axis) are equipped. Each one of centering units 3A... consists of a frame, which moves along the X-axis, a pair of fixing clamps to Z-axis direction 33 and 34, which approaches by equal amount along the vertical axis (which makes a Z-axis) normal to the Xa-axis so as to pinch the timber, a pair of fixing clamps to Y-axis direction 31 and 32, which approach by equal amount along the horizontal axis (which makes a Y-axis) normal to the Xa-axis so as to pinch the timber, and a mechanism 39, which translates the whole fixing clamps to the Y-axis direction 31 and 32 in parallel to the Y-axis and the Z-axis directions.