PURPOSE: To improve safety and facilitate use by continuously swinging a saw assembly from a lifted stationary position, engaging a lower guard with an extended part, and opening the lower guard.

CONSTITUTION: A saw assembly 16 is swung downward around an axis 18, for cutting off a workpiece positioned on a table contacting with a fence 42. An extended part 35 is engaged with the cam face 103 of a flange 100, and thereby downward movement of the saw assembly 16 further opens a lower guard 40. The lower guard 40 is perfectly drawn inside an upper guard 32. Before the lower guard 49 is brought in contact with the workpiece, the lower guard 40 is always opened by the extended part 35, but it is formed not to open so much that the saw blade 26 is exposed over and before the workpiece to the extent being endangered.