To provide a machining apparatus suitable for cutting a back material, the so-called triangular material into a plate shape.

The machining apparatus is equipped with a plurality of rotary blades 3 provided in a rotatable manner, a table 2 and a moving means 6 for moving the table 2 in a rotary blade direction. A V-shaped groove 7 having the deepest part at the position of the center line in the longitudinal direction of the table 2 is formed to the table 2 when looked in the direction crossing the center line in the longitudinal direction of the table 2 at a right angle and a plurality of rotary blade-inserting grooves 5 are provided corresponding to the rotary blades 3.