Abstract: A series of apertures are formed in a blade of a circular saw which define a plurality of the strips interconnecting the toothed annular peripheral portion and the inside portion of the blade. The strips are dimensioned so as not to hinder the expansion of the peripheral portion and the width of the peripheral portion is so great that its own weight can bring about the required tension due to the centrifugal force when the blade rotates. The width of the peripheral portion is 10-30% of the diameter of the blade and the length of the flexible part of the strips is at least 10% of the diameter of the blade. The flexibility, defined by the formulaK=(L/B).times.(sin .alpha./N)in which L=the length of the center line of the flexible portion of the rib and B=the greatest width of the rib of this length, .alpha.