A demolition shear has a pair of pivotably movable elongated jaws each having a pivot portion and an elongated jaw portion extending therefrom. The lower jaw portion has a cutter side wall, a guide side wall and an outer end wall, and the cutter side wall has an upper working surface with a generally V-shaped configuration, and a recess providing a blade seating shoulder extending parallel to the upper surface. The end shoulder at the proximal end intersects at an obtuse angle with the blade seating shoulder, and defines a reference plane. Seated on the shoulder are abutting; elongated rhimboidal lower cutter blades with end faces extending parallel to the reference plane. The outer end wall has an inner surface portion has a blade seating shoulder on its inner surface on which is seated a cross cutter blade. The guide side wall has a recess adjacent the outer end wall which provides a blade seating shoulder on which is seated a guide blade. The distal end surfaces of the guide and distal cutter blades extend parallel to the reference plane and bear firmly against the cross cutter blade which also lies in parallel plane. The upper jaw has an invention V-shape pivot portion and a jaw portion extending therefrom with a cutter side surface adjacent the cutter side surface of the lower jaw and a guide side surface. Its cutter side surface has a recess providing a blade seating shoulder on which is seated a pair of abutting elongated rhomboidal upper cutter blades.